<PAGE>   1

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM 10-K


[X] Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act
of 1934 (Fee Required) for the fiscal year ended March 31, 2001

                                       OR

[ ] Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange
Act of 1934 (No Fee Required) for the transition period from __________ to
__________

                         Commission file number 0-11363

                             Chad Therapeutics, Inc.
             (Exact name of registrant as specified in its charter)

<TABLE>
<S>                                                  <C>
              California                                  95-3792700
   (State or other jurisdiction of                    (I.R.S. Employer
    incorporation or organization)                   Identification No.)
</TABLE>

             21622 Plummer Street, Chatsworth, CA       91311
           (Address of principal executive offices)   (Zip Code)

       Registrant's telephone number, including area code: (818) 882-0883

        Securities registered pursuant to Section 12(b) of the Act: None.

           Securities registered pursuant to Section 12(g) of the Act:

                          Common Shares, $.01 par value
                                (Title of class)

       Indicate by check mark whether the Registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
Registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.   Yes [X]   No [ ]

       Indicate by check mark if disclosures of delinquent filers pursuant to
Item 405 of Regulation SK (229.405 of this chapter) is not contained herein, and
will not be contained, to the best of registrant's knowledge, in definitive
proxy or information statements incorporated by reference in Part III of this
Form 10-K or any amendment to this Form 10-K. [ ]

       The aggregate market value of the voting shares held by non-affiliates of
the Registrant on June 12, 2001 (based on the closing price of such stock on the
American Stock Exchange on such date) was $22,114,000.


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       Indicate the number of shares outstanding of each of the registrant's
classes of common stock as of June 12, 2001:

       Common Shares                                        10,052,000

       Portions of the Registrant's definitive Proxy Statement for its September
12, 2001, Shareholders' meeting ("Proxy Statement") (which Proxy Statement has
not been filed as of the date hereof) are incorporated into Part III as set
forth herein. Portions of the Registrant's Annual Report to Shareholders for the
year ended March 31, 2001 ("Annual Report") are incorporated into Part II as set
forth herein and only such portions of the Annual Report as are specifically
incorporated by reference are thereby made a part of this Annual Report on Form
10-K.


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                                     PART I

Item 1. Business

       Chad Therapeutics, Inc. ("CHAD" or the "Company") was organized in
August, 1982, to develop, produce and market respiratory care devices designed
to improve the efficiency of oxygen delivery systems for both home and hospital
treatment of patients who require supplemental oxygen. The Company introduced
its first respiratory care device in the market in June, 1983, and has
introduced additional respiratory care devices in subsequent years.

Pulmonary Disease and Oxygen Therapy

       The Company was organized to pursue the development and marketing of
devices, which improve the efficiency of systems used to administer oxygen to
patients requiring supplemental oxygen. These are primarily patients suffering
from chronic obstructive pulmonary diseases.

       Chronic obstructive pulmonary diseases (COPD) are progressive,
debilitating conditions that affect millions of Americans, severely limiting
their activities and shortening their lives. Such conditions, which include
chronic bronchitis, emphysema and severe asthma, decrease the capacity of the
lungs to oxygenate the blood. To make up for this deficiency, it is common
medical practice to administer supplemental oxygen, usually on a 24 hours per
day basis in an amount sufficient to increase blood oxygenation to near normal
levels.

       According to the National Heart, Lung and Blood Institute of the National
Institutes of Health (NIH) between 1980 and 1990 the death rate from COPD
increased by 22% in the United States.

       More recently, the American Lung Association reported that in 1996 there
were 16.4 million Americans suffering from COPD, which is the fourth leading
cause of death in the United States and claimed the lives of over 100,000 people
that year. This report also notes that in 1996 the annual cost to the nation for
COPD in health care and indirect costs was estimated to be $31.9 billion.

       Although precise data are not available, various individual and
institutional sources and reports estimate that there are more than 1 million
home care patients receiving supplementary administration of oxygen. Total
dealer revenues for home oxygen therapy were estimated at over $2 billion for
1996. Medicare, which accounts for about 60% of home oxygen dealers' revenues,
expected to spend almost $1.5 billion in 1996 for home oxygen as compared to
$1.4 billion in 1995 according to officials of the Congressional Budget Office.
Market revenues for home oxygen grew at 8-10% per year during the five year
period ending in 1995 and, based on a 1999 Frost and Sullivan market survey, are
currently growing at an average rate of 5% per year. This is due to the
increasing number of COPD patients as well as the move to home care and out of
hospitals. Growth in the number of home oxygen patients is projected by the
Congressional Budget Office to continue at a rate of approximately 8% per year
through 2002.

       Chronic obstructive pulmonary diseases are also prevalent in other
countries, particularly in some European nations and the Far East where the
incidence is higher than in the United States. The potential international
market for home oxygen is expected to grow to 150% of the U.S. market over the
next five to ten years.

       The primary oxygen supply for home patients is provided from cylinders
containing compressed gaseous oxygen (less than 1% of users), reservoirs
containing liquid oxygen (10-15%) or by means of concentrators which concentrate
oxygen from the ambient air (85-90%).

       Standard oxygen delivery systems are characteristically inefficient,
permitting over 67% of the oxygen supply delivered to the patient to be wasted,
primarily because the oxygen is administered steadily


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to the patient, even while he is exhaling. Since the normal breathing cycle
consists of an exhalation period which is approximately twice as long as the
inhalation period, at least two-thirds of the oxygen from this continuous flow
system is wasted. Furthermore, it is generally accepted that the oxygen breathed
in during the first one-third of the inhalation period provides most of the
oxygenation benefit to the patient.

       In June, 1989, the home oxygen market changed. A new procedure for
payment by Medicare for home oxygen services became effective. This procedure
provides a prospective flat fee monthly payment based solely on the patient's
prescribed oxygen requirement and disregards modality, the type of system in
use. Prior to that time, dealers were reimbursed on the basis of total oxygen
delivered by the dealer with variances based on the modality used and other
variables. The prior procedure tended to encourage waste and inefficiency.
Consequently, with the incentive to operate efficiently, inexpensive
concentrators have grown in popularity because of their low cost and less
frequent servicing requirements. At the same time interest heightened in oxygen
conserving devices which can extend the life of oxygen supplies and reduce
service calls by dealers. There is also a separate fixed allowance from Medicare
for patients who need to be mobile and therefore require portable oxygen
systems.

       In January, 1998, the monthly amount that Medicare reimburses for home
oxygen was reduced by 25% and an additional 5% reduction was implemented in
January, 1999. While the long term impact of this reduction may be to cause home
care dealers to seek products that provide even greater cost saving
efficiencies, the concerns over the size of these cuts has, in many cases,
resulted in the provision of systems to patients that do not provide truly
ambulatory oxygen.

       While these cost pressures have intensified, mobility has increased in
importance as the treatment of pulmonary patients has moved away from hospitals
and into home care. Also, leading authorities now state that maintenance and
improvement of the patient's quality of life should be a major objective in the
treatment of COPD. Maintaining quality of life and compliance with prescribed
exercise programs require that the patient be as mobile as possible and thus
increase the demand for portable oxygen equipment.

CHAD's Products

       Recognizing the need for more efficient oxygen delivery systems, the
Company has pursued, since its inception, the development and marketing of
devices that are designed to conserve oxygen. The benefits of such improvements
include substantial cost savings and increased mobility for ambulatory patients
who require portable oxygen supplies. These devices extend the life of oxygen
supplies, make possible more compact and longer lasting portable systems and
thereby improve the quality of life for home oxygen patients.

       OXYMIZER(R) and OXYMIZER Pendant Oxygen-Conserving Devices. In June,
1983, the Company began marketing its first product, the OXYMIZER disposable
oxygen-conserving device, a unique, patented, disposable device developed to
provide up to 4 to 1 savings of oxygen when used with any oxygen supply source.

       The OXYMIZER device contains a collapsible reservoir, which captures
incoming oxygen delivered during expiration and prevents its waste. The oxygen
captured in this reservoir is then inhaled by the patient during the first
instant of his next inspiration. The OXYMIZER device thus both conserves oxygen
and provides the patient with an extra rich supply of oxygen at the beginning of
the inhalation period when it can be most effectively utilized.

       Extensive clinical testing and trials over the past eighteen years have
repeatedly demonstrated that patients using the OXYMIZER device are able to
achieve equivalent blood oxygenation levels while using significantly less
oxygen. There have been more than 32 clinical evaluations from institutions
worldwide that have confirmed the efficacy and oxygen savings of the OXYMIZER
devices.


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       The greater efficiency provided by the OXYMIZER devices over standard
oxygen delivery systems also permits home health care patients to achieve
greater mobility by enabling them to use smaller portable cylinders or by
obtaining two to four times the life from standard sized portable cylinders.

       For home oxygen dealers the disposable OXYMIZER devices afford the cost
advantages of oxygen conservation without capital investment in expensive
equipment.

       In hospitals the OXYMIZER devices are reported to be frequently used for
maintenance of certain patients requiring higher flow levels of oxygen without
having to resort to uncomfortable oxygen masks.

       The Company is pursuing a marketing strategy that emphasizes the cost
savings, efficiencies and level of patient comfort associated with the use of
the OXYMIZER devices. See "Marketing" and "Competition".

       The OXYMIZER Pendant device is similar to the OXYMIZER device, except
that its reservoir is located in a "pendant" which hangs over the patient's
chest rather than under the nose. The OXYMIZER Pendant has a more traditional
appearance than the OXYMIZER. The Company began marketing the OXYMIZER Pendant
in August, 1984.

       OXYMATIC(R) Electronic Oxygen Conservers. The Company began marketing the
OXYMATIC conserver in March, 1986. This product is a small electronic device,
designed for use with portable oxygen systems. The OXYMATIC conserver
electronically senses the optimal moment in the breathing cycle for delivery of
oxygen and at that moment, releases a very brief pulse of oxygen to the patient.
The OXYMATIC conserver concentrates the administration of oxygen during the
first one-third of the inhalation phase, when oxygen is most efficiently
utilized. Through its optimal efficiency the OXYMATIC electronic conserver makes
possible oxygen savings ratios of from 4 to 1 up to 12 to 1 depending on the
user's breathing rate. In clinical experience the average saving has been shown
to be 7 to 1 - about twice the efficiency of most competitive products. There
have been at least twelve controlled clinical trials and studies of patient
groups using the OXYMATIC conserver, all of which have confirmed its efficacy
and efficiency.

       In May, 1995, the Company introduced the OXYMATIC Model 301 which
replaced the previous model. This model incorporates improved electronics,
providing a longer battery life and other improvements which make it more user
friendly.

       In June, 1993, the Company introduced a different version of the OXYMATIC
conserver, the OXYMATIC - 2400. This model incorporates substantial improvements
and additional features, such as an alarm system, which are designed to allow it
to be used 24 hours a day with both primary and portable oxygen sources. The
OXYMATIC - 2400 conserver affords the same oxygen savings ratios as the original
OXYMATIC conserver.

       In July, 2000, the Company introduced the first of the OXYMATIC 400
series of conservers. Additional models were added to this line in January and
March of 2001. This new line of conservers was designed to capitalize on the
proven reliability and efficiency of the Company's previous models. In addition,
features and options were added to create state-of-the-art conservers that would
give homecare providers a wide choice of products to service their patient's
individual needs and preferences. These new conservers include a built-in
regulator, expanded flow rates and provide an average savings of 5 to 1 over
continuous flow oxygen.

       Sales of OXYMATIC conservers and the OXYLITE systems discussed below
accounted for approximately 42% of the Company's sales in 2001.


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       OXYLITE(R) Complete Portable Oxygen System. The Company also markets
eight OXYLITE complete portable oxygen systems, each of which is available with
either the OXYMATIC Model 301 conserver or the OXYMATIC - 2400 conserver. These
systems combine the OXYMATIC conserver with small, lightweight oxygen cylinders
and lightweight pressure regulators in an attractive carrying pouch.

       The OXYMATIC 301 and 2400 conservers extend the time the contents of the
cylinders will last by an average of seven times. They provide ambulatory
patients with greater mobility and less weight. These systems offer a superior
alternative to commonly used liquid oxygen systems for mobile patients and are
more cost effective for homecare dealers to supply.

       OXYCOIL(R) Coiled Oxygen Tubing. In January, 1986, the Company began
marketing the OXYCOIL coiled oxygen tubing, a device which replaces the standard
supply tubing for the OXYMIZER devices, the OXYMATIC conserver or conventional
nasal cannulas. The OXYCOIL tubing is a convenience and safety device which can
be used with any oxygen system to help keep the supply tubing out of the
patients' way, thus minimizing the tripping and tangling problems associated
with standard supply tubing.

       TOTAL O(2)(R) Delivery System. In January, 1998, the Company began
marketing the TOTAL O(2) Delivery System. This system provides stationary oxygen
for patients at home, portable oxygen including an oxygen conserving device for
ambulation and a safe and efficient mechanism for filling portable oxygen
cylinders. This should provide home care dealers with a means to deal with the
25% and 5% cuts in home oxygen reimbursement that went into effect on January 1,
1998 and 1999,respectively, by allowing them to reduce the monthly cost of
servicing patients while at the same time providing the patients with a higher
quality of service. This can be accomplished as the home care dealer will no
longer be required to make regular monthly service calls to deliver full
portable cylinders and the patient will no longer be dependent on the dealer for
those deliveries to obtain full cylinders.

       Initial sales of the TOTAL O(2) system were adversely affected by several
factors, including the overall home oxygen market climate as well as start-up
manufacturing and supplier issues. The Company has taken a number of steps to
resolve the manufacturing and supplier issues. The Company believes the sales
potential for this product is significant as the average selling price is
approximately four times that of the OXYMATIC and OXYLITE systems. No assurances
can currently be given regarding the level of success the Company may achieve
with the TOTAL O(2) system. See Outlook: Issues & Risks - New Product in the
Company's Annual Report to Shareholders.

       The technology for each of the devices described above belongs to the
inventors thereof. The Company has acquired exclusive licenses to manufacture
and market the OXYMIZER devices, the OXYMATIC conservers, the OXYCOIL tubing and
the TOTAL O(2) system. See "Licensing and Related Agreements".

       Other Products. The Company also offers a variety of ancillary products
that support the principal oxygen conserving products. These include oxygen
cylinders of various sizes and compositions, regulators, cannulas and connecting
tubing and assorted carrying pouches. In addition, with a field sales force of
manufacturer's representatives covering the entire United States (see
"Marketing") the Company will utilize this team as part of a strategy to market
and sell additional products that are targeted for the Company's current
customer base, the homecare provider. The Company began marketing and selling
the first of these in December of 2000 and as other opportunities arise
additional products may be added to this portfolio.

Products Under Development

       It is the Company's objective to continuously improve and add to its
oxygen conserving and related products. In April, 1996, the Company entered into
an exclusive development contract with an


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outside vendor to develop unique oxygen therapy products. The first product
developed from the project was the TOTAL O(2) system. During the fiscal year
ended March 31, 2000, the Company entered into contracts with outside vendors to
develop two new products in the oxygen conserver field. No assurance can be
given that any products developed pursuant to these contracts will be
successfully marketed or that the Company will ever derive significant revenues
or earnings from the sale of such products.

Research and Development

       For the year ended March 31, 2001, the Company expended approximately
$658,000 on research and development and has expended approximately $4,519,000
since its inception in August, 1982. The Company operates in an industry that is
subject to rapid technological change, and its ability to compete successfully
depends upon, among other things, its ability to stay abreast or ahead of new
technological developments. Accordingly, the Company expects to expend
increasing amounts for the development or acquisition of new products or the
improvement of existing products. In the next fiscal year the Company expects to
spend approximately $830,000 on several projects. The Company conducts research
and development internally and also utilizes the services of outside firms and
consultants for its research and development activities.

Licensing and Related Agreements

       The Company has entered into license agreements (the "Inventors License
Agreements") with Brian L. Tiep, M.D., Robert E. Phillips and Ben A. Otsap, the
inventors of the OXYMIZER device (the "Inventors"), with respect to that device
and each of the additional oxygen conserving devices developed by them. At the
present time, the Company has licensed the OXYMIZER device, the OXYMIZER Pendant
device and the OXYMATIC conserver, thereby acquiring exclusive rights to
manufacture and market such products.

       Pursuant to the Inventors License Agreements, the Inventors grant to the
Company an exclusive license (with the right to grant sublicenses) to
manufacture, use and sell such device. The Inventors License Agreements provide
that the Company pay royalties to the Inventors on the net proceeds of sales of
the device covered by the agreement at the rate of 6% on amounts up to $10
million and 3% on amounts of $10 million or more. The Inventors License
Agreements also provide that the Company pay minimum advance royalties for each
license year in the amount of $10,000 for each year. The advance payments are to
be applied toward royalties payable for the corresponding license year, and any
amounts paid by the Company under one agreement (except those on the OXYMIZER
device), in excess of the minimum, may be applied by the Company against the
minimum payable under any other such agreement. The Company is obligated to
prosecute and defend, at its own expense, any infringement suits related to
manufacture or sale of each device covered by any such agreement.

       Each Inventors License Agreement continues until the expiration of the
last to expire of any patent covering the related device or, if no patent is
issued, for 17 years. The Inventors may terminate the Inventors License
Agreements at an earlier date if the Company is in arrears for 60 days on any
royalty payment or if the Company defaults in performing any other term of the
agreement and fails to cure such default within 60 days.

       The Company has also entered into a license agreement (the "Litton
License Agreement") with the Life Support Division of Litton Systems, Inc. for
the TOTAL O(2) Delivery System. Pursuant to the Litton License Agreement, the
Licensor grants to the Company an exclusive license (with the right to grant
sublicenses) to manufacture, use and sell such device in the health care market.
The Litton License Agreement provides that the Company pay royalties to the
Licensor on the net proceeds of sales of the device covered by the agreement at
the rate of 4% and requires minimum annual royalties of $100,000, $300,000 and
$500,000 in 1999, 2000 and subsequent years, respectively. The Litton License
Agreement continues until the expiration of the last to expire of any patent
covering the related device or until the Company ceases uses of the licensed
technology. The Licensors may terminate the Litton License


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Agreement at an earlier date if the Company is in arrears for 30 days on any
royalty payment or if the Company defaults in performing any other material
obligation of the agreement and fails to cure such default within 30 days.

Manufacturing and Sources of Supply

       The Company tests and packages its products in its own facility. Some
other manufacturing processes are conducted by other firms and the Company
expects to continue using outside firms for certain manufacturing processes for
the foreseeable future. All outside manufacturing is conducted under the
supervision and control of the Company and with tooling provided by the Company.

       Pursuant to an oral agreement, the Company purchases semi-finished units
of the OXYMIZER and OXYMIZER Pendant devices from a supplier in Southern
California. Final assembly and packaging are completed at the Company's
facilities. The Company does not contemplate entering into a formal written
agreement for these units. This arrangement is terminable at will by either
party. The Company believes that other injection molding facilities would be
available in the event of a termination of this arrangement.

       Production of the OXYMATIC Model 301, 2400 and 400 series conservers is
being handled internally with only a portion of electronic assembly being
subcontracted outside the Company. The Company is currently subcontracting with
two electronic assembly facilities and believes that other facilities would be
available in the event of an interruption of supply from the existing
facilities.

       Pursuant to oral agreements, the Company purchases components for its
OXYLITE systems (other than the OXYMATIC conserver) from several suppliers.
These arrangements are terminable at will and the Company believes other
suppliers would be available in the event of termination of these arrangements.

       Production of the TOTAL O(2) system is being handled internally with a
number of subassemblies being subcontracted outside the Company. The Company
believes that there are alternate sources of supply for these subassemblies,
including internal manufacturing as production quantities increase.

       The Company is not aware of any shortages of materials necessary for the
manufacture of its products. The Company provides customers the right to return
merchandise for credit and requires payment within a time frame consistent with
industry standards.

Marketing

       The Company's products are designed to reduce the cost of health care
while maintaining or enhancing the therapeutic benefits to the patient, and
improving the user's quality of life. The Company's marketing efforts have
focused primarily on providing home oxygen suppliers with products that they can
utilize to increase their revenues and provide a better quality of care at less
cost.

       Homecare dealers have reportedly increased their revenues by using the
Company's OXYLITE complete portable oxygen systems or by locally assembling
small portable systems incorporating the Company's OXYMATIC conserver as a
vehicle to attract new and additional patients to their business. The Company
believes these lightweight, long-lasting portable systems have both high
professional and patient acceptance which allows the supplier promoting these
products to attract new and additional customers. The Company has been advised
that medical professionals, who frequently refer patients to specific home
oxygen suppliers, find that these systems assist patients in more easily
complying with prescribed exercise programs and help them to achieve the
therapeutic benefits of maintaining a lifestyle as normal as possible. Patients,
most of whom are free to select their oxygen supplier, are reportedly receptive
to changing suppliers in order to obtain equipment that will allow them to
travel and maintain their quality of life.


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       A large portion of home oxygen patients are covered by Medicare or other
government programs. Since June 1989, home oxygen suppliers have been reimbursed
on a fixed monthly fee basis by Medicare. The monthly reimbursement amount does
not vary, as in the past, with either the type of oxygen delivery equipment
provided or the amount of oxygen supplied. Since monthly per patient revenues
are fixed, home oxygen suppliers can only increase their per patient
profitability by reducing costs. The Company's oxygen conserving products and
TOTAL O(2) Delivery System allow these suppliers to decrease their costs while
providing their patients with improved therapeutic benefits and quality of life.

       While the home respiratory care dealer remains the primary focus of the
Company's marketing efforts, this focus has been augmented by a major effort to
increase professional awareness. Promotional programs target respiratory care
physicians, nurses and therapists.

       The Company markets its products directly to home oxygen suppliers
throughout the U.S. The Company currently has a Director of Sales & Marketing,
two regional sales managers, an art and media manager, a marketing coordinator,
a Customer Relations Manager and five in-house sales and customer service
representatives who are in regular and frequent proactive telephone sales
contact with customers and potential customers. In addition, the Company has a
field sales force of independent manufacturer's sales representatives to handle
direct selling to customers. This field sales force is currently comprised of 36
individuals with coverage throughout the United States. The Company also
utilizes direct mail, trade show attendance, trade advertising and a web site to
promote the benefits of its products to home care dealers. Additionally, the
Company actively seeks to increase professional awareness of its products
through professional advertising and participation in professional meetings.

       Home oxygen therapy markets outside the United States are, in most cases,
at a much earlier stage of development. In many countries, these patients are
cared for in institutional settings. As the trend develops to move patients into
home care, opportunities for the Company's products should increase. Sales of
the OXYMATIC conserver in Canada and Japan have become an important part of the
Company's business. During 2000 the Company added an Asia/Pacific manufacturer
representative to support distributors in this region. Based on industry market
research projections, the Company expects the international market to increase
to 150% of the U.S. potential over the next five to ten years.

       The Company has entered into exclusive distributorship agreements in
Germany, Canada, Japan, Australia and several other countries. The Company's
largest distributor in Germany covers portions of the European Community. The
Company also has non-exclusive distributors in many other countries.

       Sales outside of the United States subjects the Company to certain risks,
including those involving political and economic factors, interruption of
shipments of products, currency fluctuations and devaluations and governmental
restrictions and regulations.

Customers, Backlog and Orders

       The Company presently has an active list of over 4,000 dealer and
hospital customers. Based upon information developed from various lists the
Company believes that there are approximately 7,000 to 8,000 oxygen dealers and
3,000 general hospitals in the United States which are potential customers or
customer sources for the Company. Of these 7,000 to 8,000 homecare providers,
approximately 30% are represented by three major national chain accounts. No one
customer exceeded 10% of net sales in 2001, 2000 and 1999.


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                  Financial Information Relating to Foreign and
                      Domestic Operations and Export Sales

<TABLE>
<CAPTION>
                                 2001            2000            1999
                               -------          ------          ------
<S>                            <C>              <C>             <C>
Sales (thousands):
  United States                $10,126          11,508          12,350
  Germany                          751              40             642
  All other countries            1,281           1,226           1,072
                               -------          ------          ------
  Total                        $12,158          12,774          14,064
                               =======          ======          ======
</TABLE>

       All identifiable assets are located in the United States.

       At March 31, 2001, the Company had no backlog of orders for any of its
products. The Company presently intends to maintain a large enough inventory to
ship all of its products immediately upon receipt of orders. The Company
believes that such an inventory is necessary to meet the requirements of its
customers.

Competition

       The Company is aware of several demand valve, electronically controlled
devices currently being marketed. Of these devices, those that have been the
principal competitors of the OXYMATIC conserver in the past were targeted
primarily to a specific segment of the market - liquid oxygen usage. Several
companies, including Invacare, Mallinkrodt (Nellcor/Puritan Bennett) and
Sunrise/De Vilbiss, market small (3.4 to 5.5 lbs.) portable liquid oxygen
systems incorporating simple oxygen conserving devices which double the useful
life of these systems. These units are more expensive than OXYLITE systems and
still require the supplier to make frequent and costly oxygen deliveries. The
Company does not know the levels of sales achieved by the companies marketing
these systems.

       Several of these competitors are now marketing combinations of
conservers, regulators and small cylinders in direct competition with the
Company's OXYLITE systems. Many of these products utilize conservers that
provide 2:1 to 3:1 savings ratios. As a result, these units while weighing about
the same as similar OXYLITE systems provide only 1/3 or 1/2 of the ambulation
time provided by OXYLITE systems. In addition, the Company is aware of two
companies marketing oxygen conserving devices which claim similar oxygen savings
ratios as the OXYMATIC conserver. The Company believes that some of these
competitors have been able to offer their oxygen conservers as part of a bundle
of products with perceived pricing advantages over the Company's products. In
addition, some of these competitors have introduced conservers with features not
found in the Company's products prior to the introduction of the OXYMATIC 400
series conservers. While the reliability and superior conservation of the
OXYMATIC conservers partially offset these advantages, some of these companies
have attained market share at the Company's expense. The Company does not know
the level of sales achieved by these companies.

       There are several other types of portable oxygen systems which compete
with the Company's OXYLITE systems but do not utilize oxygen conserving devices.
Aluminum and steel oxygen cylinders with continuous flow regulators are utilized
by some oxygen suppliers as portable systems. Although they do provide users
with some portability, their size and bulk limits their use by patients who need
or want to be truly ambulatory. The most commonly used of these cylinders is
approximately three feet high, weighs over 20 lbs., and provides an average
patient with less than 5 hours of oxygen. These systems are enjoying some level
of success due to their lower unit price advantage. The OXYMATIC conservers
allow the use of smaller, lighter cylinders and thus provides greater mobility.

       Until the availability of OXYLITE systems and the previously cited
changes in Medicare oxygen reimbursement, liquid oxygen was the modality of
choice for truly mobile users. Portable liquid oxygen systems that weigh 3.4 to
10 lbs., provide an average patient with 6 to 8 hours of oxygen, compared to the


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smallest OXYLITE system which weighs 4.5 lbs. and provides an average patient
with 7.3 hours of oxygen. These systems are more costly than OXYLITE systems and
require frequent and expensive (often weekly) deliveries of bulk liquid oxygen
to the patient's home. Although many oxygen suppliers continue to use and re-use
existing inventories of liquid oxygen equipment to service ambulatory patients,
purchases of new liquid oxygen equipment by home care dealers is decreasing.

       The Company is aware of one combination oxygen concentrator and refilling
station being marketed in competition with the TOTAL O(2) system by Invacare.
This system is larger and heavier and does not contain some of the integrated
features found in the TOTAL O(2) system. The Company does not know the level of
sales achieved by the company marketing this system.

Patents and Trademarks

       The Company regards the products that it develops or licenses and its
manufacturing processes as proprietary and relies on a combination of patents,
trademarks, trade secret laws and confidentiality agreements to protect its
rights in its products. U.S. patents have been issued covering the original
OXYMIZER device, the OXYMIZER Pendant device, the OXYMATIC conserver and the
TOTAL O(2) Delivery System. A number of foreign patent applications pertaining
to the Company's activities have also been issued.

       The Company pursues a policy of obtaining patents for appropriate
inventions related to products marketed or manufactured by the Company. The
Company considers the patentability of products developed for it to be
significant to the success of the Company. To the extent that the products to be
marketed by the Company do not receive patent protection, competitors may be
able to manufacture and market substantially similar products. Such competition
could have an adverse impact upon the Company's business.

       There can be no assurance that patents, domestic or foreign, will be
obtained with respect to the Company's products, or that, if issued, they will
provide substantial protection or be of commercial benefit to the Company. In
addition, the patent laws of foreign countries may differ from those of the
United States as to the patentability of the Company's products and processes
and, accordingly, the degree of protection afforded by foreign patents may be
more or less than in the United States.

       In the United States, although a patent has a statutory presumption of
validity, the issuance of a patent is not conclusive as to such validity or as
to the enforceable scope of its claims therein. The validity and enforceability
of a patent can be attacked by litigation after its issuance by the U.S. Patent
and Trademark Office. If the outcome of such litigation is adverse to the owner
of the patent in that the patent is held to be invalid, other parties may then
use the invention covered by the patent. Accordingly, there can be no assurance
that patents with respect to the Company's products, if issued, will afford
protection against competitors with similar products, nor can there be any
assurance that the patents will not be infringed upon or designed around by
others. Moreover, no assurance can be given that the Company's products will not
infringe on the intellectual property rights claimed by others.

       The Company has obtained U.S. registration for the trademarks "OXYMIZER",
"OXYMATIC", "CHAD", "OXYCOIL" and "TOTAL O(2)". A series of foreign applications
to register the trademark "OXYMIZER" in a number of countries of commercial
interest to the Company have been filed.

Governmental Regulation

       The commercialization of the OXYMIZER, OXYMATIC and TOTAL O(2) devices is
subject to the Federal Food, Drug and Cosmetic Act (the "Food and Drug Act") and
to regulations issued thereunder. The Company anticipates that commercialization
of other devices that it intends to market will also be subject to the Food and
Drug Act. The Food and Drug Act is administered by the FDA, which has authority
to regulate the marketing, manufacturing, labeling, packaging and distribution
of products


                                       11

<PAGE>   12
subject to the Food and Drug Act. In addition, there are requirements under
other federal laws and under state, local and foreign statutes that may apply to
the manufacture and marketing of the Company's products. The Medical Device
Amendments of 1976 to the Food and Drug Act (the "Amendments") and the Safe
Medical Device Act of 1990 significantly extended the authority of the FDA to
regulate the commercialization of medical devices. The Amendments established
three classifications of medical devices: Class I, Class II and Class III. With
respect to all three classes, the general provisions of the Food and Drug Act
prohibit adulteration and misbranding. A medical device may be adulterated if
the device is or could be adversely affected by its methods of manufacture,
storage or packaging. A medical device may be misbranded if its labeling is
false or misleading or if its labeling does not contain specific information
required by law applicable to such type of device. In addition, failure to
register a medical device covered under the Food and Drug Act will render it
misbranded under the Food and Drug Act.

       All manufacturers of medical devices must register with the FDA and, with
their initial registration, list all medical devices produced by them. This
listing must be updated annually. In addition, prior to commercial distribution
of additional devices, the manufacturer must file with the FDA and receive
approval prior to the commencement of such commercial distribution, a notice
setting forth certain information about the device, including the classification
into which the manufacturer believes it falls.

       Class I devices are subject only to the general controls concerning
adulteration, misbranding, good manufacturing practices, record keeping and
reporting requirements. Class II devices must, in addition, comply with
performance standards as promulgated by the FDA.

       The Company has registered with the Bureau of Medical Devices of the FDA
as a Medical Device Establishment and with the Department of Health Services of
the State of California as a Medical Device Manufacturer. In addition, the
Company has developed procedures to comply with FDA standards concerning good
manufacturing practices, record keeping and reporting and is ISO 9001 certified.

       The Company has filed notification submissions pursuant to Section 510(k)
of the Food and Drug Act of its intent to market the OXYMIZER, the OXYMIZER
Pendant, the OXYMATIC conserver, the OXYCOIL and the TOTAL O(2) Delivery System;
it has been granted permission by the FDA to market the OXYMIZER and the
OXYMIZER Pendant as Class I devices. Permission has been granted to market the
OXYMATIC, the OXYCOIL and TOTAL O(2) Delivery System as Class II devices.

Employees

       As of June 12, 2001, CHAD had 91 full-time employees and 1 part-time
employee. Sixty-two of the Company's employees are engaged in manufacturing and
the remainder are engaged in marketing, sales, administration and management.
None of the Company's employees are represented by unions; the Company believes
its employee relations are satisfactory. The Company will employ additional
personnel in all phases of its activities as required by the growth in its
activities. The number of additional personnel will be dependent on sales levels
of individual products.

Item 2. Properties.

       The Company's offices and manufacturing facilities are situated in
premises located in Chatsworth, California and consist of approximately 55,500
square feet, at a monthly rental fee of $28,662 pursuant to a lease expiring in
June, 2003. Management believes this facility should adequately handle the
Company's needs for the foreseeable future. The Company does not own any real
property and does not anticipate acquiring any in the foreseeable future.


                                       12
<PAGE>   13
Item 3. Legal Proceedings.

       The Company becomes involved in legal proceedings in the ordinary course
of business. The Company maintains product liability insurance in an amount it
deems customary in the industry for protection of the Company against potential
product liability claims. Although the Company believes its product liability
insurance is sufficient and no pending legal proceeding poses a material threat,
no assurance can be given that pending or future proceedings will not have a
material impact on the Company's financial condition or results of operations.

Item 4. Submission of Matters to a Vote of Security Holders.

       Not applicable.


                                     PART II

Item 5. Market for Registrant's Common Equity and Stockholder Matters.

       The information required herein is hereby incorporated by reference to
the information contained under the caption "Corporate Data" in the Company's
Annual Report.

Item 6. Selected Financial Data.

       The information required herein is hereby incorporated by reference to
the information contained under the caption "Selected Financial Data" in the
Company's Annual Report.

Item 7. Management's Discussion and Analysis of Financial Condition and Results
of Operations.

       The information required herein is hereby incorporated by reference to
the information contained under the caption "Management's Discussion and
Analysis of Financial Condition and Results of Operations" in the Company's
Annual Report.

Item 7a. Quantitative and Qualitative Disclosures about Risk.

       The Company has no significant risks in this area.

Item 8. Financial Statements and Supplementary Data.

       The information required herein is hereby incorporated by reference to
the Financial Statements and the Notes thereto contained in the Company's Annual
Report.

Item 9. Disagreements on Accounting and Financial Disclosure.

       None.

                                    PART III

Item 10. Directors and Executive Officers of the Registrant.

       The information required herein is hereby incorporated by reference to
the information appearing under the captions "Election of Directors" and
"Executive Officers" in the Company's definitive Proxy Statement to be filed
with the Securities and Exchange Commission.


                                       13
<PAGE>   14

Item 11. Executive Compensation.

       The information required herein is hereby incorporated by reference to
the information appearing under the caption "Compensation of Directors and
Executive Officers" in the Company's definitive Proxy Statement to be filed with
the Securities and Exchange Commission.

Item 12. Security Ownership of Certain Beneficial Owners and Management.

       The information required herein is hereby incorporated by reference to
the information appearing under the caption "Voting Securities and Principal
Holders Thereof" in the Company's definitive Proxy Statement to be filed with
the Securities and Exchange Commission.

Item 13. Certain Relationships and Related Transactions.

       None.

                                     PART IV

Item 14. Exhibits, Financial Statement Schedules, and Reports on Form 8-K.

       (a) (1) Financial Statements.

              Included in Part II of this Report:

                     Independent Auditors' Report

                     Balance Sheets -- March 31, 2001 and 2000

                     Statements of Operations -- Years ended March 31, 2001,
                     2000 and 1999.

                     Statements of Shareholders' Equity -- Years ended March 31,
                     2001, 2000 and 1999.

                     Statements of Cash Flows -- Years ended March 31, 2001,
                     2000 and 1999.

                     Notes to Financial Statements.

       (a) (2) Financial Statement Schedules.

              See Notes to Financial Statements.

           (3) Exhibits.

              3.1   Articles of Incorporation of the Registrant, as amended*****

              3.2   Bylaws of the Registrant, as amended*

              10.3 OXYMIZER License Agreement, as amended, with Robert E.
              Phillips, Brian L. Tiep, M.D. and Ben A. Otsap*

              10.5 Pulser System License Agreement, as amended, with Robert E.
              Phillips, Brian L. Tiep, M.D. and Ben A. Otsap.  (The Pulser
              System is now called the OXYMATIC.)*

              10.7 OXYMIZER Pendant License Agreement, as amended, with Robert
              E. Phillips, Brian L. Tiep, M.D. and Ben A. Otsap*


                                       14
<PAGE>   15

              10.20 OXYCOIL tubing License Agreement with Mary Smart (licensed
              under the name Respi-Coil).***

              10.23  Summary plan description for Chad Therapeutics, Inc.
              Employee Savings and Retirement Plan****

              10.24  1994 Stock Option Plan******

              10.25  Lease on real property at 21622 Plummer Street, Chatsworth,
              California******

              10.26 TOTAL O(2) Delivery System License Agreement, as amended,
              with the Life Support Division of Litton Industries, Inc.*******

              13.1 Annual Report to Shareholders for the year ended March 31,
              2001.

              23.1  Consent of Independent Accountant

              28.1 Letter from the FDA authorizing the Company to market the
              OXYMIZER oxygen conserving device as a Class 1 device.*

              28.2 Letter from the FDA authorizing the Company to market the
              OXYMIZER Pendant oxygen conserving device as a Class 1 device.**

              28.5 Letter from the FDA authorizing the Company to market the
              OXYMATIC electronic oxygen conserver as a Class 2 device.***

              28.6 Letter from the FDA authorizing the Company to market the
              OXYCOIL coiled oxygen tubing as a Class 2 device.***

              28.7 Letter from the FDA authorizing the Company to market the
              TOTAL O2 Delivery System as a Class 2 device*******

              28.9 Letter from the FDA authorizing the Company to market the
              OXYMATIC 411 conserver as a Class 2 device

              28.10 Letter from the FDA authorizing the Company to market the
              OXYMATIC 401A and 411A conservers as a Class 2 devices

       (b)    Reports on Form 8-K - None filed.

       (c)    Index to Exhibits.

       (d)    Financial Statement Schedules - None

----------

* Previously filed as an Exhibit to the Registrants' Registration Statement on
Form S-18, File No. 2-83926.

** Previously filed as an Exhibit to the Registrants' Annual Report on Form 10-K
for the year ended March 31, 1984.

*** Previously filed as an Exhibit to the Registrants' Annual Report on Form
10-K for the year ended March 31, 1986.

**** Previously filed as an Exhibit to the Registrants' Annual Report on Form
10-K for the year ended March 31, 1993. ***** Previously filed as an exhibit to
the Registrant's Annual Report on Form 10-K for the year ended March 31, 1994.

****** Previously filed as an exhibit to the Registrant's Annual Report on Form
10-K for the year ended March 31, 1996.

******* Previously filed as an exhibit to the Registrant's Annual Report on Form
10-K for the year ended March 31, 1998.


                                       15
<PAGE>   16

                                   SIGNATURES

       Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the Registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized, in the City of Los
Angeles, State of California, on the 20th day of June, 2001.

                                   CHAD THERAPEUTICS, INC.


                                   By /s/ Thomas E. Jones
                                      ------------------------------------------
                                      Thomas E. Jones, Chief Executive Officer

       Pursuant to the requirements of the Securities Exchange Act of 1934, this
report has been signed below by the following persons on behalf of the
Registrant and in the capacities and on the dates indicated.

<TABLE>
<CAPTION>
    Signature                                       Title                                      Date
<S>                                <C>                                                     <C>
/s/ Thomas E. Jones                Chief Executive Officer, President and                  June 20, 2001
--------------------------------   Director (Principal Executive Officer)
Thomas E. Jones


/s/ Earl L. Yager                  Chief Operating Officer, Chief Financial                June 20, 2001
--------------------------------   Officer and Secretary and Director
Earl L. Yager                      (Principal Financial and Accounting Officer)


/s/ David L. Cutter                Director                                                June 20, 2001
--------------------------------
David L. Cutter


/s/ John C. Boyd                   Director                                                June 20, 2001
--------------------------------
John C. Boyd


/s/ Norman Cooper                  Director                                                June 20, 2001
--------------------------------
Norman Cooper


/s/ Philip Wolfstein               Director                                                June 20, 2001
--------------------------------
Philip Wolfstein


/s/ James M. Brophy                Director                                                June 20, 2001
--------------------------------
James M. Brophy
</TABLE>


                                       16
<PAGE>   17

                                  Exhibit Index


<TABLE>
<CAPTION>
                                      Exhibit Index                                    Sequentially
Exhibit No.                             Document                                       Numbered Page
-----------                           -------------                                    -------------
<S>            <C>                                                                     <C>
  13.1         Annual Report to Shareholders for the year ended March 31, 2001

  23.1         Consent of Independent Accountants

  28.9         Letter from the FDA authorizing the Company to market the
               OXYMATIC 411 conserver as a Class 2 device

  28.10        Letter from the FDA authorizing the Company to market the
               OXYMATIC 401A and 411A conservers as a Class 2 devices
</TABLE>


                                       17