<PAGE>   1

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

                             ---------------------

                                   FORM 10-Q

                             ---------------------

(MARK ONE)

   [X]          QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                  FOR THE QUARTERLY PERIOD ENDED JUNE 30, 1999

                                       OR

   [ ]         TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d)
                         OF THE SECURITIES ACT OF 1934

                         COMMISSION FILE NUMBER 0-19946

                             LINCARE HOLDINGS INC.
             (Exact name of registrant as specified in its charter)

<TABLE>
       <S>                                                  <C>
                   DELAWARE                                      51-0331330
       (State or other jurisdiction of                        (I.R.S. Employer
        incorporation or organization)                      Identification No.)

        19337 US 19 NORTH, SUITE 500,                              33764
                CLEARWATER, FL                                   (Zip Code)
   (Address of principal executive offices)
</TABLE>

      Registrant's telephone number, including area code:  (727) 530-7700

     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 the number of shares outstanding of each of the issuer's classes
of common stock, as of the latest practicable date.

<TABLE>
<CAPTION>
                           CLASS                              OUTSTANDING AT JULY 31, 1999
                           -----                              -----------------------------
<S>                                                           <C>
Common Stock, $0.01 par value...............................        58,233,117 shares
</TABLE>

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<PAGE>   2

                             LINCARE HOLDINGS INC.

                                   FORM 10-Q
                  FOR THE QUARTERLY PERIOD ENDED JUNE 30, 1999

                                     INDEX

<TABLE>
<CAPTION>
                                                                      PAGE
                                                                      ----
<S>     <C>                                                           <C>
PART I.  FINANCIAL INFORMATION
Item 1  Financial Statements (unaudited)
           Condensed consolidated balance sheets....................    3
           Condensed consolidated statements of operations..........    4
           Condensed consolidated statements of cash flows..........    5
           Notes to condensed consolidated financial statements.....    6
Item 2  Management's Discussion and Analysis of Results of
        Operations and Financial Condition..........................    7
Item 3  Quantitative and Qualitative Disclosure Regarding Market
        Risk........................................................    9

PART II. OTHER INFORMATION
Item 1  Legal Proceedings...........................................    9
Item 2  Changes in Securities.......................................    9
Item 3  Defaults Upon Senior Securities.............................    9
Item 4  Submission of Matters to a Vote of the Security Holders.....   10
Item 5  Other Information...........................................   10
Item 6  Exhibits and Reports on Form 8-K............................   10

SIGNATURE...........................................................   11
</TABLE>

                                        2
<PAGE>   3

                     LINCARE HOLDINGS INC. AND SUBSIDIARIES

                     CONDENSED CONSOLIDATED BALANCE SHEETS

<TABLE>
<CAPTION>
                                                               JUNE 30,      DECEMBER 31,
                                                                 1999            1998
                                                              -----------    ------------
                                                              (UNAUDITED)
                                                                    (IN THOUSANDS)
<S>                                                           <C>            <C>
Current assets:
  Cash and cash equivalents.................................    $    625       $  5,100
  Accounts and notes receivable.............................      93,029         85,187
  Income tax receivable.....................................       4,626          3,553
  Inventories...............................................       3,029          2,908
  Prepaid expenses..........................................         762            478
                                                                --------       --------
          Total current assets..............................     102,071         97,226
                                                                --------       --------
Property and equipment......................................     288,118        246,033
Less: accumulated depreciation..............................     125,185        105,799
                                                                --------       --------
          Net property and equipment........................     162,933        140,234
                                                                --------       --------
Other assets:
  Goodwill..................................................     392,723        336,485
  Intangible assets.........................................       9,137          6,102
  Covenants not to compete..................................       1,294          1,772
  Other.....................................................         918            820
                                                                --------       --------
          Total other assets................................     404,072        345,179
                                                                --------       --------
               Total assets.................................    $669,076       $582,639
                                                                ========       ========

Current liabilities:
  Current installments of long-term obligations.............    $ 15,305       $ 12,923
  Accounts payable..........................................      20,992         19,169
  Accrued expenses:
     Compensation and benefits..............................       9,324         10,679
     Other..................................................       6,362          5,377
                                                                --------       --------
          Total current liabilities.........................      51,983         48,148
                                                                --------       --------
Long-term obligations, excluding current installments.......      55,073         22,258
Deferred income taxes.......................................      15,651         15,651
Minority interest...........................................         804            926
Stockholders' equity:
  Common stock..............................................         584            583
  Additional paid-in capital................................     129,882        128,828
  Retained earnings.........................................     415,398        367,085
  Less: treasury stock......................................         299            840
                                                                --------       --------
          Total stockholders' equity........................     545,565        495,656
                                                                --------       --------
               Total liabilities and stockholders' equity...    $669,076       $582,639
                                                                ========       ========
</TABLE>

     See accompanying notes to condensed consolidated financial statements.

                                        3
<PAGE>   4

                     LINCARE HOLDINGS INC. AND SUBSIDIARIES

                CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                              FOR THE THREE MONTHS ENDED    FOR THE SIX MONTHS ENDED
                                              ---------------------------   -------------------------
                                                JUNE 30,       JUNE 30,      JUNE 30,      JUNE 30,
                                                  1999           1998          1999          1998
                                              ------------   ------------   -----------   -----------
                                                  (IN THOUSANDS EXCEPT SHARE AND PER SHARE DATA)
<S>                                           <C>            <C>            <C>           <C>
Net revenues................................  $   143,025    $   119,518    $   279,106   $   231,422
                                              -----------    -----------    -----------   -----------
Costs and expenses:
  Costs of goods and services...............       22,032         18,681         43,629        36,700
  Operating expenses........................       32,466         27,643         63,403        54,283
  Selling, general and administrative
     expenses...............................       31,728         26,647         61,723        52,119
  Bad debt expense..........................        1,716          1,434          3,349         2,777
  Depreciation expense......................       10,300          8,565         19,850        16,575
  Amortization expense......................        3,977          2,966          7,767         5,951
                                              -----------    -----------    -----------   -----------
                                                  102,219         85,936        199,721       168,405
                                              -----------    -----------    -----------   -----------
          Operating income..................       40,806         33,582         79,385        63,017
                                              -----------    -----------    -----------   -----------
Other income (expense):
  Interest income...........................           57            159            106           284
  Interest expense..........................         (745)          (129)        (1,397)         (216)
  Net loss on disposal of property and
     equipment..............................          (37)           (23)           (45)          (34)
                                              -----------    -----------    -----------   -----------
                                                     (725)             7         (1,336)           34
                                              -----------    -----------    -----------   -----------
          Income before income taxes........       40,081         33,589         78,049        63,051
Income taxes................................       15,271         12,865         29,736        24,149
                                              -----------    -----------    -----------   -----------
          Net income........................  $    24,810    $    20,724    $    48,313   $    38,902
                                              ===========    ===========    ===========   ===========
Income per common share.....................
  Basic.....................................  $      0.43    $      0.36    $      0.83   $      0.67
                                              ===========    ===========    ===========   ===========
  Diluted...................................  $      0.42    $      0.35    $      0.82   $      0.66
                                              ===========    ===========    ===========   ===========
Weighted average number of common shares
  outstanding...............................   58,376,441     57,960,693     58,365,959    57,771,955
                                              ===========    ===========    ===========   ===========
Weighted average number of common shares and
  common share equivalents outstanding......   59,251,608     59,365,322     59,309,156    59,392,340
                                              ===========    ===========    ===========   ===========
</TABLE>

     See accompanying notes to condensed consolidated financial statements.

                                        4
<PAGE>   5

                     LINCARE HOLDINGS INC. AND SUBSIDIARIES

                CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                              FOR THE SIX MONTHS ENDED
                                                              ------------------------
                                                              JUNE 30,       JUNE 30,
                                                                1999           1998
                                                              ---------      ---------
                                                                   (IN THOUSANDS)
<S>                                                           <C>            <C>
Cash from operations........................................  $ 71,805       $ 63,599
Investing activities:
  Proceeds from sale of property and equipment..............       108             68
  Capital expenditures......................................   (38,426)       (29,865)
  (Increase) decrease in other assets.......................       (98)            35
  Business acquisitions, net of cash acquired...............   (46,231)       (34,784)
                                                              --------       --------
                                                               (84,647)       (64,546)
                                                              --------       --------
Financing activities:
  Proceeds from long-term obligations.......................    91,000         18,000
  Payment of long-term obligations..........................   (83,747)       (19,887)
  Decrease in minority interest.............................      (220)          (253)
  Proceeds from issuance of common stock....................       794          6,060
  Treasury stock issued.....................................       540          1,071
                                                              --------       --------
                                                                 8,367          2,849
                                                              --------       --------
Increase (decrease) in cash.................................    (4,475)         1,902
Cash and cash equivalents, beginning of period..............     5,100          4,078
                                                              --------       --------
Cash and cash equivalents, end of period....................  $    625       $  5,980
                                                              ========       ========
</TABLE>

     See accompanying notes to condensed consolidated financial statements.

                                        5
<PAGE>   6

                             LINCARE HOLDINGS INC.

              NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
                                  (UNAUDITED)

NOTE 1 -- BASIS OF PRESENTATION

     The accompanying condensed consolidated balance sheet as of June 30, 1999,
the condensed consolidated statements of operations for the three and six month
periods ended June 30, 1999 and 1998 and the condensed consolidated statements
of cash flows for the six months ended June 30, 1999 and 1998 are unaudited. In
the opinion of management, all adjustments, consisting of normal recurring
accruals, necessary for a fair presentation of the results of operations for the
interim periods presented have been reflected herein. The results of operations
for interim periods are not necessarily indicative of the results to be expected
for the entire year. The accompanying condensed consolidated balance sheet as of
December 31, 1998 is derived from the Lincare Holdings Inc. (the "Company")
audited balance sheet as of that date.

NOTE 2 -- BUSINESS COMBINATIONS

     During the six months ended June 30, 1999 the Company acquired, in
unrelated acquisitions, the stock of four companies and certain assets of three
companies. Each acquisition was accounted for as a purchase. The results of the
acquired companies are included in the accompanying consolidated statements of
operations since the respective dates of acquisition.

     The aggregate cost of these acquisitions was as follows:

<TABLE>
<CAPTION>
                                                              (IN THOUSANDS)
                                                              --------------
<S>                                                           <C>
Cash........................................................     $46,231
Deferred acquisition obligations............................       7,065
Assumption of liabilities...................................      20,968
                                                                 -------
                                                                 $74,264
                                                                 =======
</TABLE>

     The aggregate purchase price was allocated as follows:

<TABLE>
<S>                                                              <C>
Current assets..............................................     $ 2,316
Property and equipment......................................       4,275
Intangible assets...........................................       5,257
Goodwill....................................................      62,416
                                                                 -------
                                                                 $74,264
                                                                 =======
</TABLE>

     Unaudited pro forma supplemental information on the results of operations
for the six months ended June 30, 1999 and June 30, 1998 are provided below and
reflect the acquisitions as if they had been combined at the beginning of each
respective period.

<TABLE>
<CAPTION>
                                                                FOR THE SIX MONTHS
                                                                  ENDED JUNE 30,
                                                              ----------------------
                                                                1999          1998
                                                              --------      --------
                                                               (IN THOUSANDS EXCEPT
                                                                 PER SHARE DATA)
<S>                                                           <C>           <C>
Net revenues................................................  $287,466      $251,432
                                                              ========      ========
Net income..................................................  $ 48,976      $ 41,567
                                                              ========      ========
Income per common share:
  Basic.....................................................  $   0.84      $   0.72
                                                              ========      ========
  Diluted...................................................  $   0.83      $   0.70
                                                              ========      ========
</TABLE>

     The unaudited pro forma financial information is not necessarily indicative
of either the results of operations that would have occurred had the
transactions been effected at the beginning of the respective preceding periods
or of future results of operations of the combined companies.

                                        6
<PAGE>   7

                             LINCARE HOLDINGS INC.

                    MANAGEMENT'S DISCUSSION AND ANALYSIS OF
                 RESULTS OF OPERATIONS AND FINANCIAL CONDITION

BALANCED BUDGET ACT OF 1997

     On August 5, 1997, the Balanced Budget Act of 1997 ("BBA") was signed into
law. This legislation, among other things, reduces Medicare expenditures by $115
billion over five years. The BBA reduces Medicare payment amounts for oxygen and
oxygen equipment furnished after January 1, 1998, to 75 percent of the fee
schedule amounts in effect during 1997. Payment amounts for oxygen and oxygen
equipment furnished after January 1, 1999, and each subsequent year are reduced
to 70 percent of the fee schedule amounts in effect during 1997.

     The BBA freezes the Consumer Price Index (U.S. urban average) update for
covered items of durable medical equipment for each of the years 1998 through
2002 while limiting fees for parenteral and enteral nutrients, supplies and
equipment to 1995 reasonable charge levels over the same period. The BBA reduces
payment amounts for covered drugs and biologicals to 95 percent of the average
wholesale price of such covered items for each of the years 1998 through 2002.

     The BBA authorizes the Department of Health and Human Services to conduct
up to five competitive bidding demonstration projects for the acquisition of
durable medical equipment and requires that one such project be established for
oxygen and oxygen equipment. Each demonstration project is to be operated over a
three-year period and is to be conducted in not more than three competitive
acquisition areas. The BBA also includes provisions designated to reduce health
care fraud and abuse including a surety bond requirement for durable medical
equipment providers.

OPERATING RESULTS

     The following table sets forth for the periods indicated a summary of the
Company's net revenues by source:

<TABLE>
<CAPTION>
                                          FOR THE THREE MONTHS    FOR THE SIX MONTHS ENDED
                                             ENDED JUNE 30,               JUNE 30,
                                          --------------------    ------------------------
                                            1999        1998         1999          1998
                                          --------    --------    ----------    ----------
                                                           (IN THOUSANDS)
<S>                                       <C>         <C>         <C>           <C>
Oxygen and other respiratory therapy....  $128,639    $107,157     $250,258      $207,145
Home medical equipment and other........    14,386      12,361       28,848        24,277
                                          --------    --------     --------      --------
          Total.........................  $143,025    $119,518     $279,106      $231,422
                                          ========    ========     ========      ========
</TABLE>

     Net revenues for the three months ended June 30, 1999 increased by
$23,507,000 (or 19.7%) compared with the three months ended June 30, 1998, and
for the six months ended June 30, 1999 increased $47,684,000 (or 20.6%) compared
with the six months ended June 30, 1998. The price cuts attributable to the BBA
reduced the Company's revenues by approximately $4,685,000 and $9,205,000 for
the three and six months ended June 30, 1999. Excluding the effect on the
Company's revenues from the Medicare price reductions, internally generated
growth increased revenues by approximately $13,713,000 (or 11.5%) and
$27,648,000 (or 11.9%) for the three and six months ended June 30, 1999. Growth
due to acquisitions increased revenues by approximately $14,479,000 (or 12.1%)
for the three months ended June 30, 1999 and $29,241,000 (or 12.6%) for the six
months ended June 30, 1999 over the comparable prior year period.

     Cost of goods and services as a percentage of net revenues were 15.4% for
the three months ended June 30, 1999 compared with 15.6% for the three months
ended June 30, 1998. Costs of goods and services as a percentage of net revenues
were 15.6% for the six months ended June 30, 1999 compared with 15.9% for the
six months ended June 30, 1998.

     Operating expenses as a percentage of net revenues were 22.7% for the three
months ended June 30, 1999 as compared to 23.1% for the three months ended June
30, 1998. Operating expenses as a percentage of net revenues were 22.7% for the
six months ended June 30, 1999 compared with 23.5% for the six months ended June
30, 1998.

                                        7
<PAGE>   8

     Selling, general and administrative expenses as a percentage of net
revenues were 22.2% for the three months ended June 30, 1999 compared with 22.3%
for the three months ended June 30, 1998. Selling, general and administrative
expenses as a percentage of net revenues were 22.1% for the six months ended
June 30, 1999 compared with 22.5% for the six months ended June 30, 1998.

     Amortization expense for the three months ended June 30, 1999 increased to
$3,977,000 compared with $2,966,000 for the three month period ending June 30,
1998. Amortization expense for the six months ended June 30, 1999 increased to
$7,767,000 compared with $5,951,000 for the six month period ended June 30,
1998. The increase is attributable to the amortization of intangible assets
associated with business combinations in 1998 and the first half of 1999.

     Operating income for the three and six months ended June 30, 1999 increased
to $40,806,000 and $79,385,000, respectively, compared with $33,582,000 and
$63,017,000 for the three and six months ended June 30, 1998. The increases in
operating income are attributable to the continued revenue growth and efforts to
control costs. The Company has been able to maintain a cost structure that, with
increases in net revenues, allows the Company to spread its fixed costs over a
larger base of revenues, resulting in improvements in operating income.

LIQUIDITY AND CAPITAL RESOURCES

     Net cash provided from operating activities was $71,805,000 for the six
months ended June 30, 1999 compared with $63,599,000 for the six months ended
June 30, 1998.

     Net cash used in investing and financing activities was $76,280,000 for the
six months ended June 30, 1999 compared with $61,697,000 for the six months
ended June 30, 1998. Activity during the six-month period ended June 30, 1999
included the Company's investment of $46,231,000 in business acquisitions,
investment in capital equipment of $38,426,000, proceeds of $91,000,000 from
long-term obligations, and payments of $83,747,000 related to long-term
obligations.

     On June 11, 1999, the Company's Board of Directors authorized the Company
to repurchase up to $200 million of its outstanding common stock. Purchases will
be made through open market or privately negotiated transactions, subject to
market conditions and trading restrictions.

YEAR 2000 REMEDIATION

     Certain risks may exist with respect to potential malfunctions of computer
hardware and software and embedded microprocessors due to the upcoming change in
the century (the "Year 2000 problem"). Malfunctions may arise due to the design
of microchips and microprocessors and computer systems that are programmed to
use two rather than four digits to define the applicable year. The Company is
involved in an extensive, ongoing program to identify and remediate potential
issues arising from the Year 2000 problem.

     The Company uses a proprietary and internally developed management
information system (MIS) which serves as the platform for the operating and
financial activities of the Company. The MIS system processes billings to and
collections from third party payors for services provided by the Company and
supports all of the Company's accounting, finance and general ledger functions.
The system provides management with information used to measure and evaluate
performance levels throughout the Company including revenues and profitability,
accounts receivable and collections, equipment controls and utilization,
customer activity and manpower trends. The Company has completed, in all
material respects, the conversion of its mission-critical MIS software thereby
mitigating the risk of Year 2000 problems. The costs associated with this
conversion were immaterial and fully expensed in the prior fiscal year.

     The Company is assessing its use of ancillary, third party computer
software used to electronically submit medical claims to certain payors. In the
event that the use of this software is impacted by the Year 2000 problem, the
Company's contingency plan includes the submission of paper claims to such
payors. The Company does not believe that this will have a material effect on
the Company's ability to receive payment for services rendered.

                                        8
<PAGE>   9

     Certain medical devices and equipment provided by the Company to its
customers may contain embedded technology such as microprocessors that could be
affected by the Year 2000 problem. The Company has identified those categories
of devices and equipment that may be sensitive to the change in century, and has
developed a plan to determine the Year 2000 status of specific items. In the
event that the Company identifies specific devices and equipment that are not
Year 2000 compliant, or the Company is unable to determine the status of such
items, the Company will remove such items from service and replace them with
therapeutically comparable, Year 2000 compliant equipment from alternate
vendors. The Company does not believe that the scope and cost of exchanging
non-compliant devices and equipment will have a material impact on the Company's
financial position.

     The Company is highly dependent upon certain government and private payors
for payment of claims for services and equipment provided by the Company. The
Company is in the process of determining the Year 2000 compliance of computer
systems used by third party payors to process claims for medical services and
equipment submitted by the Company for payment. The Company cannot be assured of
the timely remediation of third party claims processing and payment systems. The
failure by a significant third party payor to correct Year 2000 problems, to the
extent that such issues delay or prevent timely or appropriate payment of
claims, could have a material impact on the Company's cash flow from operations.
The Company is monitoring the Year 2000 progress of Medicare Part B carriers,
and other government agencies and private payors with which the Company does
significant business, to determine the potential impact to the Company. The
Company is also in the process of determining the contingency plans of these
payors to release payments to providers such as the Company in the event of
claims processing system failures. Such plans may include cash advances to
providers based on historical payment trends or processing claims on paper
rather than in an electronic format.

QUANTITATIVE AND QUALITATIVE DISCLOSURE REGARDING MARKET RISK

     The Company had no derivative securities as of June 30, 1999. The Company
is exposed to changes in interest rates as a result of its bank credit agreement
which is based on the London Interbank Offered Rate.

     A 10% increase in interest rates related to the Company's bank credit
facility would not have a material effect on the Company's earnings over the
next fiscal year or the bank credit agreement's fair value.

FORWARD LOOKING STATEMENTS

     Statements contained in this Form 10-Q that are not based on historical
facts are forward looking statements, subject to uncertainties and risks,
including, but not limited to, the constantly changing health care environment,
potential reductions in reimbursement by government and third party payors for
the Company's products and services, the demand for the Company's products and
services, economic and competitive conditions, the availability of appropriate
acquisition candidates and the successful completion of acquisitions, access to
borrowed and/or equity capital on favorable terms, and other risks detailed in
the Company's Securities and Exchange Commission filings.

PART II.  OTHER INFORMATION

Item   1    Legal Proceedings

     As previously disclosed by the Company on November 17, 1998, a qui tam
complaint against the Company was unsealed in the U.S. District Court in the
Northern District of Georgia on November 6, 1998. On August 2, 1999, the Company
was served with this complaint. If such service is valid and the case proceeds,
the Company intends to vigorously defend this suit. The duration or outcome of
this matter cannot be predicted with any degree of certainty.

Items  2-3  Not Applicable.

                                        9
<PAGE>   10

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

     The Annual Meeting of Shareholders of the Company was held on May 10, 1999.
The following matters were voted on at the Annual Meeting, with the number of
votes cast for, against or withheld, as applicable in each case, indicated next
to each such matter:

     1.     Election of Directors



                                               FOR       WITHHELD
                                            ----------   --------

            J.T. Kelly                      54,656,721    56,285
            J.P. Byrnes                     54,656,656    56,350
            C.B. Black                      54,654,748    58,258
            F.T. Cary                       54,647,748    65,258
            T.O. Pyle                       54,654,748    58,258
            W.F. Miller, III                54,654,748    58,258

     2.     Ratification of selection of KPMG LLP as the Company's independent
            accountants for the fiscal year ending December 31, 1999:

            For: 56,694,266          Against: 11,306          Abstain: 7,434

     3.     Approval of the amendment to the 1998 Stock Plan to increase by
            500,000 the number of shares available under the 1998 Stock Plan:

            For: 38,945,099          Against: 15,743,045      Abstain: 24,862


Item   5    Not Applicable.

Item   6    Exhibits and Reports on Form 8-K

     (a) Exhibits:


EXHIBIT
NUMBER                                   EXHIBIT
-------                                  -------

 27.0     --   Financial Data Schedule (for SEC Use Only)


     (b) The Company did not file a Current Report on Form 8-K during the three
months ended June 30, 1999.

                                       10
<PAGE>   11

                                   SIGNATURE

     Pursuant to the requirements 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.

                                                  Lincare Holdings Inc.
                                          --------------------------------------
                                                        Registrant

                                                    /s/  PAUL G. GABOS
                                          --------------------------------------
                                                         Paul G. Gabos
                                            Secretary, Chief Financial Officer
                                             and Principal Accounting Officer

August 11, 1999

                                       11