<PAGE>   1
 
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                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549
 
                            ------------------------
 
                                   FORM 10-Q
 
[X]   QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
      EXCHANGE ACT OF 1934
 
                 FOR THE QUARTERLY PERIOD ENDED MARCH 31, 1999
 
                                       OR
 
[ ]   TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
      EXCHANGE ACT OF 1934
 
        FOR THE TRANSITION PERIOD FROM                TO
 
                         COMMISSION FILE NUMBER 1-13275
 
                             OUTDOOR SYSTEMS, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
<TABLE>
<S>                                            <C>
                   DELAWARE                                      86-0736400
         (STATE OR OTHER JURISDICTION                         (I.R.S. EMPLOYER
              OF INCORPORATION)                             IDENTIFICATION NO.)
</TABLE>
 
<TABLE>
<S>                                             <C>
2502 N. BLACK CANYON HIGHWAY, PHOENIX, ARIZONA                       85009
   (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)                       (ZIP CODE)
</TABLE>
 
                                 (602) 246-9569
               REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE
 
     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.
 
                               [X] Yes     [ ] No
 
     Number of Common Shares outstanding at May 10, 1999:  184,493,307 SHARES.
 
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<PAGE>   2
 
                                    CONTENTS
 
<TABLE>
<CAPTION>
                                                              PAGE
                                                              ----
<S>                                                           <C>
PART I -- FINANCIAL INFORMATION
ITEM 1.  Unaudited Financial Statements
Condensed Consolidated Balance Sheets as of March 31, 1999
  and December 31, 1998.....................................    1
Condensed Consolidated Statements of Operations for the
  Three Months ended March 31, 1999 and 1998................    2
Condensed Consolidated Statements of Comprehensive Income
  for the Three Months ended March 31, 1999 and 1998........    3
Condensed Consolidated Statements of Cash Flows for the
  Three Months ended March 31, 1999 and 1998................    4
Notes to Condensed Consolidated Financial Statements........    5
ITEM 2.  Management's Discussion and Analysis of Financial
         Condition and Results of Operations................    7
ITEM 3.  Quantitative and Qualitative Disclosures About
  Market Risk...............................................   10
PART II -- OTHER INFORMATION
ITEM 1.  Legal Proceedings..................................   10
ITEM 2.  Changes in Securities and Use of Proceeds..........   10
ITEM 3.  Defaults Upon Senior Securities....................   10
ITEM 4.  Submission of Matters To a Vote of Security
  Holders...................................................   10
ITEM 5.  Other Information..................................   10
ITEM 6.  Exhibits and Reports on Form 8-K...................   10
SIGNATURES..................................................   11
</TABLE>
<PAGE>   3
 
                                     PART I
 
                             FINANCIAL INFORMATION
 
ITEM 1.  FINANCIAL STATEMENTS
 
                             OUTDOOR SYSTEMS, INC.
 
                     CONDENSED CONSOLIDATED BALANCE SHEETS
 
<TABLE>
<CAPTION>
                                                             MARCH 31,     DECEMBER 31,
                                                               1999            1998
                                                            -----------    ------------
                                                            (UNAUDITED)
                                                            (IN THOUSANDS, EXCEPT SHARE
                                                                AND PER SHARE DATA)
<S>                                                         <C>            <C>
                                        ASSETS
Current Assets:
  Cash and cash equivalents...............................  $   14,095      $   16,554
  Accounts receivable, net................................     142,262         136,817
  Prepaid land leases.....................................      27,201          23,467
  Other current assets....................................      18,815          14,544
  Value added taxes receivable............................      33,876          33,876
  Deferred income taxes...................................      12,550          12,546
                                                            ----------      ----------
     Total current assets.................................     248,799         237,804
Property and Equipment, Net...............................   1,899,507       1,876,065
Other Assets..............................................      18,066          15,881
Deferred Financing Costs..................................      33,308          35,070
Goodwill and Other Intangibles, Net.......................     592,462         592,006
                                                            ----------      ----------
                                                            $2,792,142      $2,756,826
                                                            ==========      ==========
                         LIABILITIES AND STOCKHOLDERS' EQUITY
Current Liabilities:
  Accounts payable........................................  $    9,857      $   12,855
  Accrued interest........................................      25,787           8,696
  Accrued expenses and other liabilities..................      49,810          48,208
  Current maturities of long-term debt....................     147,041         130,247
                                                            ----------      ----------
     Total current liabilities............................     232,495         200,006
Long-term Debt............................................   1,661,890       1,676,985
Other Long-term Obligations...............................       9,880           9,688
Deferred Income Taxes.....................................      99,626          99,221
                                                            ----------      ----------
     Total liabilities....................................   2,003,891       1,985,900
                                                            ----------      ----------
Common Stockholders' Equity:
  Preferred stock, $1.00 par value -- authorized
     12,000,000 shares; no shares issued and outstanding
  Common stock, $.01 par value -- authorized, 600,000,000
     shares; issued and outstanding 184,476,206 and
     184,369,963 shares...................................       1,845           1,844
  Additional paid-in capital..............................     763,092         762,775
  Retained earnings.......................................      36,054          31,305
  Treasury stock at cost -- 36,235,206 shares.............      (3,794)         (3,794)
  Accumulated other comprehensive loss....................      (8,946)        (21,204)
                                                            ----------      ----------
     Total common stockholders' equity....................     788,251         770,926
                                                            ----------      ----------
                                                            $2,792,142      $2,756,826
                                                            ==========      ==========
</TABLE>
 
           See notes to condensed consolidated financial statements.
                                        1
<PAGE>   4
 
                             OUTDOOR SYSTEMS, INC.
 
                CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
 
<TABLE>
<CAPTION>
                                                                    THREE MONTHS
                                                                       ENDED
                                                                     MARCH 31,
                                                          --------------------------------
                                                               1999              1998
                                                          --------------    --------------
                                                                    (UNAUDITED)
                                                          (IN THOUSANDS, EXCEPT SHARE AND
                                                                  PER SHARE DATA)
<S>                                                       <C>               <C>
REVENUES:
Outdoor advertising.....................................   $   189,889       $   163,742
Less agency commissions and discounts...................        22,440            21,138
                                                           -----------       -----------
     Total..............................................       167,449           142,604
Lease, printing and other revenues......................         4,765             4,118
                                                           -----------       -----------
     Net revenues.......................................       172,214           146,722
                                                           -----------       -----------
OPERATING EXPENSES:
Direct advertising......................................        82,608            74,873
General and administrative..............................         9,809             8,554
Depreciation and amortization...........................        35,426            27,037
                                                           -----------       -----------
                                                               127,843           110,464
                                                           -----------       -----------
Operating income........................................        44,371            36,258
OTHER:
Foreign currency transaction gain.......................          (546)             (480)
Interest expense -- net.................................        37,256            31,867
                                                           -----------       -----------
Income before income tax expense........................         7,661             4,871
INCOME TAX PROVISION....................................         2,911             2,143
                                                           -----------       -----------
NET INCOME..............................................   $     4,750       $     2,728
                                                           ===========       ===========
BASIC AND DILUTED INCOME PER SHARE:
Basic:
  Net income............................................   $       .03       $       .02
                                                           ===========       ===========
  Weighted average number of shares.....................   184,452,828       181,731,867
                                                           ===========       ===========
Diluted:
  Net income............................................   $       .02       $       .01
                                                           ===========       ===========
  Weighted average number of shares.....................   205,557,530       202,079,391
                                                           ===========       ===========
</TABLE>
 
           See notes to condensed consolidated financial statements.
                                        2
<PAGE>   5
 
                             OUTDOOR SYSTEMS, INC.
 
           CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
 
<TABLE>
<CAPTION>
                                                                THREE MONTHS
                                                                    ENDED
                                                                  MARCH 31,
                                                              -----------------
                                                               1999       1998
                                                              -------    ------
                                                                 (UNAUDITED)
                                                               (IN THOUSANDS)
<S>                                                           <C>        <C>
Net income..................................................  $ 4,750    $2,728
Other comprehensive income:
  Unrealized foreign currency translation gain..............   12,258       422
                                                              -------    ------
Comprehensive income........................................  $17,008    $3,150
                                                              =======    ======
</TABLE>
 
           See notes to condensed consolidated financial statements.
                                        3
<PAGE>   6
 
                             OUTDOOR SYSTEMS, INC.
 
                CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
 
<TABLE>
<CAPTION>
                                                               THREE MONTHS ENDED
                                                                   MARCH 31,
                                                              --------------------
                                                                1999        1998
                                                              --------    --------
                                                                  (UNAUDITED)
                                                                 (IN THOUSANDS)
<S>                                                           <C>         <C>
OPERATING ACTIVITIES:
Net income..................................................  $  4,750    $  2,728
Changes to reconcile net income to net cash provided by
  operating activities:
  Deferred taxes............................................    (1,911)        928
  Amortization of discounts on notes payable and bonds......       131         233
  Depreciation and amortization.............................    35,426      27,037
  Other.....................................................      (443)       (480)
Changes in net assets and liabilities:
  Increase in accounts receivable...........................    (5,077)     (9,869)
  Increase in prepaid expenses and other....................    (8,388)       (426)
  Increase in accrued interest..............................    17,091      16,740
  Decrease in accounts payable and other liabilities........      (149)    (11,057)
                                                              --------    --------
     Net Cash Provided by Operating Activities..............    41,430      25,834
                                                              --------    --------
INVESTING ACTIVITIES:
Acquisitions of outdoor advertising assets..................   (35,228)     (9,260)
Capital expenditures........................................   (10,246)     (7,235)
                                                              --------    --------
     Net Cash Used in Investing Activities..................   (45,474)    (16,495)
                                                              --------    --------
FINANCING ACTIVITIES:
Proceeds from long-term debt................................    22,851       9,189
Principal payments on long-term debt........................   (21,754)    (23,750)
Issuance of common stock....................................       318         100
                                                              --------    --------
     Net Cash Provided by (Used in) Financing Activities....     1,415     (14,461)
                                                              --------    --------
Effect of exchange rate changes on cash.....................       170           2
                                                              --------    --------
NET DECREASE IN CASH AND CASH EQUIVALENTS...................    (2,459)     (5,120)
CASH AND CASH EQUIVALENTS -- BEGINNING......................    16,554       5,897
                                                              --------    --------
CASH AND CASH EQUIVALENTS -- ENDING.........................  $ 14,095    $    777
                                                              ========    ========
</TABLE>
 
           See notes to condensed consolidated financial statements.
                                        4
<PAGE>   7
 
                             OUTDOOR SYSTEMS, INC.
 
              NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
                                  (UNAUDITED)
 
NOTE 1 -- BASIS OF PRESENTATION
 
     The accompanying unaudited condensed consolidated financial statements have
been prepared in accordance with generally accepted accounting principles for
interim financial information and with the instructions to Form 10-Q of
Regulation S-X. Accordingly, they do not include all of the information and
notes required by generally accepted accounting principles for complete
financial statements. In the opinion of management, all adjustments and
reclassifications considered necessary for a fair and comparable presentation
have been included and are of a normal recurring nature. Operating results for
the three months ended March 31, 1999, are not necessarily indicative of the
results that may be expected for the year ending December 31, 1999. The enclosed
financial statements should be read in conjunction with the consolidated
financial statements and notes thereto included in the Company's Form 10-K filed
with the Securities and Exchange Commission on March 15, 1999.
 
     Certain reclassifications were made to the 1998 financial statements to
conform with the 1999 presentation.
 
NOTE 2 -- INCOME PER SHARE
 
     Basic net income per share is computed based on the weighted average number
of common shares outstanding during each period. Diluted net income per share is
computed based on the weighted average number of common and common equivalent
shares outstanding during each period and includes shares issuable upon exercise
of stock options except in those circumstances where such options would be
anti-dilutive.
 
     The following is a reconciliation of basic and diluted weighted average
shares.
 
<TABLE>
<CAPTION>
                                                              THREE MONTHS ENDED
                                                                  MARCH 31,
                                                          --------------------------
                                                             1999           1998
                                                          -----------    -----------
<S>                                                       <C>            <C>
Basic weighted average shares...........................  184,452,828    181,731,867
Add:
  Shares issuable upon exercise of stock options........   21,104,702     20,347,524
                                                          -----------    -----------
Diluted weighted average shares.........................  205,557,530    202,079,391
                                                          ===========    ===========
</TABLE>
 
NOTE 3 -- NEW ACCOUNTING PRONOUNCEMENTS
 
     The Financial Accounting Standards Board issued SFAS No. 133, Accounting
for Derivative Instruments and Hedging Activities ("SFAS No. 133") which is
effective for fiscal quarters beginning after June 15, 1999, and requires all
derivative contracts to be carried on the balance sheet at their fair values.
The Company is currently evaluating the impact of SFAS No. 133 on its financial
statements.
 
NOTE 4 -- FOREIGN CURRENCY TRANSLATION
 
     In accordance with the principles of Statement of Financial Accounting
Standards ("SFAS") No. 52, "Foreign Currency Translation," the Company is using
the local currency as the functional currency of its Canadian and Mexican
operating subsidiaries. Accordingly, assets and liabilities held outside the
United States are translated into U.S. dollars at the rate of exchange in effect
at the balance sheet date. Income and expense items are translated from the
functional currency into U.S. dollars at the weighted average exchange rate
prevailing during the period.
 
                                        5
<PAGE>   8
                             OUTDOOR SYSTEMS, INC.
 
      NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
Translation gains and losses are included in other comprehensive income in the
stockholders' equity. Gains and losses resulting from foreign currency
transactions are reflected currently in the consolidated statements of
operations.
 
NOTE 5 -- SEGMENTS
 
     The Company has operations in 147 metropolitan markets throughout North
America which have similar operations, but are managed independently. No single
customer accounts for 10% or more of any segment's revenue. None of these
markets, individually, account for a significant portion of the Company's
assets, revenues or net income and, therefore, they have been aggregated by
geographical region as follows:
 
<TABLE>
<CAPTION>
                                         THREE MONTHS ENDED MARCH 31, 1999
                              --------------------------------------------------------
                                UNITED
                                STATES      CANADA     MEXICO      ELIM       TOTAL
                              ----------   --------   --------   --------   ----------
                                                   (IN THOUSANDS)
<S>                           <C>          <C>        <C>        <C>        <C>
Net revenues from external
  customers.................  $  150,468   $ 13,435   $  8,311              $  172,214
Intersegment revenues.......          --      1,226         --     (1,226)          --
Interest expense (income) --
  net.......................      35,766      1,558        (68)                 37,256
Depreciation and
  amortization expense......      27,286      2,874      5,266                  35,426
Foreign currency transaction
  (gain) loss...............          --       (657)       111                    (546)
Income tax expense
  (benefit).................       3,463      1,359     (1,911)                  2,911
Segment net income (loss)...       4,946        330       (526)                  4,750
Capital expenditures........       6,851      2,366      1,029                  10,246
Total assets................   2,628,358    180,027    391,425   (407,668)   2,792,142
</TABLE>
 
<TABLE>
<CAPTION>
                                          THREE MONTHS ENDED MARCH 31, 1998
                               -------------------------------------------------------
                                 UNITED
                                 STATES      CANADA     MEXICO     ELIM       TOTAL
                               ----------   --------   --------   -------   ----------
                                                   (IN THOUSANDS)
<S>                            <C>          <C>        <C>        <C>       <C>
Net revenues from external
  customers..................  $  133,641   $ 13,081                        $  146,722
Intersegment revenues........          --      1,899               (1,899)          --
Interest expense -- net......      30,177      1,690                            31,867
Depreciation and amortization
  expense....................      24,987      2,050                            27,037
Foreign currency transaction
  (gain) loss................          --       (480)                             (480)
Income tax expense...........       1,027      1,116                             2,143
Segment net income (loss)....       2,484        244                             2,728
Capital expenditures.........       6,005      1,230                             7,235
Total assets.................   2,114,161    149,682              (41,085)   2,222,758
</TABLE>
 
                                        6
<PAGE>   9
 
ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
        OF OPERATIONS
 
GENERAL
 
     The following discussion of the consolidated results of operations of the
Company for the three months ended March 31, 1999 and financial condition at
March 31, 1999 should be read in conjunction with the December 31, 1998
Consolidated Financial Statements of the Company and the related Notes included
therein.
 
USE OF EBITDA
 
     The performance of an outdoor advertising business, such as the Company, is
measured by its ability to generate EBITDA. EBITDA is defined as operating
income (loss) before interest, taxes, depreciation and amortization expense and
foreign currency transaction gain (loss). Although EBITDA is not a measure of
performance calculated in accordance with generally accepted accounting
principles, the Company believes that EBITDA is accepted by the outdoor
advertising industry as a generally recognized measure of performance and is
used by analysts who report publicly on the performance of outdoor advertising
companies. Nevertheless, this measure should not be considered in isolation or
as a substitute for operating income, net income, net cash provided by operating
activities or any other measure for determining the Company's operating
performance or liquidity which is calculated in accordance with generally
accepted accounting principles.
 
RESULTS OF OPERATIONS
 
     Operating results for the first quarter of 1999 include the operations of
the several acquisitions completed during 1998 (collectively the "1998
Acquisitions"), including Philadelphia Outdoor, completed on April 7, 1998,
Gator Outdoor Advertising, Inc., completed on May 19, 1998 and the acquisition
of Vendor, S.A. de C.V. and MM Billboard, S.A. de C.V. completed on July 1,
1998.
 
  Comparison of Three Months ended March 31, 1999 and March 31, 1998
 
     Gross revenues increased by 16.0% to $189.9 million in the first quarter of
1999 compared to $163.7 million in the first quarter of 1998. Gross revenues
increased approximately 8% during the first quarter of 1999 compared to the
first quarter of 1998 for markets where the Company operated both in the 1999
and 1998 periods due to increased utilization. The balance of the increased
revenues were a result of the 1998 Acquisitions.
 
     Agency commissions were 11.8% and 12.9% of gross revenues in the first
quarter of 1999 and 1998, respectively, and decreased primarily as a result of a
slightly lower proportion of revenues generated through advertising agencies in
the 1999 period.
 
     Net revenues increased by 17.4% to $172.2 million in the first quarter of
1999 from $146.7 million in the first quarter of 1998, primarily as a result of
the increase in gross revenues combined with the lower agency commissions as a
percentage of gross revenues for the first quarter of 1999.
 
     Direct advertising expenses increased to $82.6 million in the first quarter
of 1999 compared to $74.9 million in the first quarter of 1998. This was
primarily a result of the 1998 Acquisitions. As a percentage of net revenues,
direct advertising expenses were approximately 48.0% in the first quarter of
1999 compared to 51.0% in the first quarter of 1998 because of efficiencies
realized from economies of scale.
 
     General and administrative expenses increased to $9.8 million in the first
quarter of 1999 compared to $8.6 million in the first quarter of 1998. This was
primarily a result of the 1998 Acquisitions. As a percentage of net revenues
general and administrative expenses decreased to
 
                                        7
<PAGE>   10
 
approximately 5.7% in the first quarter of 1999 from 5.8% in the first quarter
of 1998 because of efficiencies realized from economies of scale.
 
     As a result of the above factors, EBITDA increased by 26.1% to $79.8
million in the first quarter of 1999 from $63.3 million in the first quarter of
1998.
 
     Depreciation and amortization expense increased to $35.4 million for the
first quarter of 1999 compared to $27.0 million in the first quarter of 1998,
primarily due to the 1998 Acquisitions, offset in part by certain assets
becoming fully depreciated during the first quarter of 1999. As a percentage of
net revenues, depreciation and amortization expense increased to 20.6% from
18.4% in the first quarter of 1999 compared to the first quarter of 1998.
 
     Interest expense increased to $37.3 million in the first quarter of 1999
compared to $31.9 million in the first quarter of 1998, as a result of interest
expense related to obligations incurred in connection with the 1998
Acquisitions. As a percentage of net revenue, interest expense decreased to
21.6% for the first quarter of 1999 compared to 21.7% for the first quarter of
1998.
 
     The Company recorded an income tax provision of $2.9 million for the first
quarter of 1999 and $2.1 million for the first quarter of 1998. The overall
effective tax rate declined due to the Mexico acquisitions.
 
LIQUIDITY AND CAPITAL RESOURCES
 
     The Company's working capital decreased to $16.3 million at March 31, 1999
compared to $37.8 million at December 31, 1998. This decrease resulted primarily
from the increase in accrued interest relating to the timing of interest
payments on subordinated debt and the increase in the current portion of
long-term debt, offset by the increase in accounts receivable and prepaid lease
rents relating to the 1998 Acquisitions.
 
     Net cash provided by operating activities increased by $15.6 million to
$41.4 million for the three months ended March 31, 1999, compared to $25.8
million for the three months ended March 31, 1998, primarily due to the increase
in net income, changes in working capital accounts and the effect of a larger
depreciation and amortization expense as a component of net income. Net cash
used in investing activities increased to $45.5 million in the first quarter of
1999 from $16.5 million in the first quarter of 1998, primarily because of
several small acquisitions made in the first quarter of 1999 and because most of
the 1998 Acquisitions did not occur until after the first quarter of 1998. Net
cash provided by financing activities was $1.4 million for the first three
months of 1999 compared to net cash used by financing activities of $14.5
million for the first three months of 1998, primarily because of net borrowings
under the senior credit facility used for acquisitions in the 1999 period.
 
     The Company made approximately $10.2 million of capital expenditures during
the first quarter of 1999, an increase from approximately $7.2 million during
the first quarter of 1998. Currently, the Company has no material commitments
for capital expenditures, although it anticipates ongoing capital expenditures
in the ordinary course of business, other than for acquisitions, will be
approximately $38.0 million to $40.0 million in each of the next two years.
 
     The Company believes that internally generated funds and available
borrowings under the senior credit facility will be sufficient to satisfy its
operating cash requirements for at least the next twelve to twenty-four months.
The Company may, however, require additional capital to consummate significant
acquisitions in the future and there can be no assurance that such capital will
be available.
 
                                        8
<PAGE>   11
 
YEAR 2000 COMPLIANCE
 
     The Company recognizes the need to ensure that its operations will not be
adversely impacted by Year 2000 software failures. The Company has identified
all significant internal information technology systems ("IT Systems") that will
require modification to ensure Year 2000 compliance ("Year 2000 Compliance").
Internal and external resources are being used to make the required
modifications and test Year 2000 Compliance for these IT Systems as well as
non-IT Systems (i.e., telephone, security, etc.) (collectively "Business
Systems"). The incremental cost to make the Business Systems year 2000 compliant
is estimated to be no more than approximately $700,000 of which approximately
$400,000 has been spent to date. The Company plans on completing all upgrades by
the end of the third quarter of 1999. These costs and the date on which the
Company plans to complete the Year 2000 modification and testing processes are
based on management's best estimates, which were derived utilizing numerous
assumptions of future events including the continued availability of certain
resources, third party modification plans and other factors. However, there can
be no guarantee that these estimates will be achieved and actual results could
differ from those plans.
 
     In addition, the Company has communicated with others with whom it does
significant business, primarily banks and suppliers of electricity, to determine
their Year 2000 Compliance readiness and the extent to which the Company is
vulnerable to any third party Year 2000 issues. There can be no guarantee that
the systems of other companies on which the Company relies will be timely
converted, or that a failure to convert by another company would not have a
material adverse effect on the Company.
 
     Based on the results of its review of the Year 2000 issues to date, the
Company does not believe that a contingency plan to handle Year 2000 problems is
necessary at this time and has not developed such a plan. The Company will,
however, continue to monitor the Year 2000 compliance program and evaluate the
need for a contingency plan to handle the most reasonably likely worst case Year
2000 scenario, which might be disruptions in service from suppliers in a few
isolated places in North America.
 
FORWARD-LOOKING STATEMENTS
 
     This report contains certain statements that are "forward-looking
statements" within the meaning of Section 27A of the Securities Act of 1933, as
amended, and Section 21E of the Securities Exchange Act of 1934, as amended.
When used in this report, the words "estimate", "expect", "anticipate",
"believe" and similar expressions are intended to identify forward-looking
statements. The Company cautions that reliance on any forward-looking statement
involves risk and uncertainties, and that although the Company believes that the
assumptions on which the forward-looking statements contained herein are based
are reasonable, any of those assumptions could prove to be inaccurate, and as a
result, the forward-looking statements based on those assumptions also could be
incorrect. The uncertainties in this regard include, but are not limited to,
those identified in the risk factors discussed under "Risk Factors" in the
Company's Prospectus dated July 24, 1997 included in the Company's Registration
Statement on Form S-4 (Reg. No. 333-30957).
 
                                        9
<PAGE>   12
 
ITEM 3.  QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
 
INTEREST RATE RISK
 
     The Company carries some floating rate debt and thus is exposed to the
impact of interest rate changes. The Company mitigates this exposure through the
use of an interest rate protection agreement which allows it to manage its mix
of variable rate and fixed rate debt. There have been no significant changes in
the Company's interest rates or in its mix of variable rate and fixed rate debt
since December 31, 1998. The Company does not enter into derivative arrangements
for trading purposes. In the event of an adverse change in interest rates,
management would likely take actions to further mitigate its exposure.
 
FOREIGN CURRENCY RISK
 
     The Company's earnings are affected by fluctuations in the value of the
U.S. dollar as compared to foreign currencies as a result of its operations in
Canada and Mexico. Both the Canadian and Mexican currencies strengthened in
relation to the U.S. dollar during the three months ended March 31, 1999.
 
     Although the Company continues to evaluate derivative financial
instruments, including forwards, swaps and purchased options, to manage foreign
currency exchange rate changes, the Company does not currently hold derivatives
for managing these risks or for trading purposes.
 
                                    PART II
 
                               OTHER INFORMATION
 
ITEM 1.  LEGAL PROCEEDINGS
 
     None.
 
ITEM 2.  CHANGES IN SECURITIES AND USE OF PROCEEDS
 
     Not applicable.
 
ITEM 3.  DEFAULT UPON SENIOR SECURITIES
 
     None.
 
ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS
 
     None.
 
ITEM 5.  OTHER INFORMATION
 
     None.
 
ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K
 
     (a) The following exhibits are filed herewith:
 
<TABLE>
<CAPTION>
EXHIBIT
  NO.                  DOCUMENT
-------                --------
<S>       <C>
  27            Financial Data Schedule
</TABLE>
 
     (b) Reports on Form 8-K.
 
        None.
 
                                       10
<PAGE>   13
 
                                   SIGNATURES
 
     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.
 
                                          OUTDOOR SYSTEMS, INC.
 
                                          By /s/ BILL BEVERAGE
                                            ------------------------------------
                                                       Bill Beverage,
                                                  Chief Financial Officer,
                                                     Secretary/Treasurer
                                               (Principal Accounting Officer)
 
Dated:  May 10, 1999
 
                                       11
<PAGE>   14
 
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
EXHIBIT
  NO.                               DOCUMENT
-------                             --------
<C>       <S>
  27      Financial Data Schedule
</TABLE>