Exhibit 99.1

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News Release

For Immediate Release



Company contacts:

T. Paul Bulmahn, Chairman and President

Albert L. Reese Jr., SVP and Chief
Financial Officer

713-622-3311 www.atpog.com



ATP Oil & Gas Corporation Reports Second Quarter 2003 Results



HOUSTON  August 15, 2003  (PRNewswire)  ATP Oil & Gas Corporation (NASDAQ: ATPG) today announced second quarter 2003
net income of $0.4 million, or $0.02 per share, from oil and natural gas production revenues of $18.6 million. Net income for the six month period ending June 30, 2003 was $2.8 million, or $0.13 per share, from oil and natural gas production
revenues of $39.1 million, compared to a loss of $3.2 million, or $0.16 per share, from oil and natural gas production revenues of $46.4 million for the six month period ending June 30, 2002. Net income in the second quarter 2002 was $3.2 million,
or $0.16 per share, from oil and natural gas production revenues of $27.7 million. Oil and natural gas production was 322 MBbls and 2,632 MMcf for the second quarter of 2003, and 665 MBbls and 5,566 MMcf for the six months ending June 30, 2003. The
Companys selected operating statistics and financial information, included within this press release, contain additional information on our activities in the second quarter and first half of 2003 and the comparable periods in 2002.



Net cash flow provided by operating activities for the six months ended June 30, 2003 was
$34.4 million, as compared to $22.4 million for the same period in 2002, representing a 54% improvement over the corresponding period. These cash flows from operating activities, plus a $10.9 million private offering have been sufficient to cover
ATPs year-to-date 2003 capital expenditures. The Company has replaced more than 200% of 2003s production through its acquisition activities. Depreciation, depletion and amortization expense per unit produced during the quarter was $1.34
per Mcfe, a 24% improvement from first quarter 2003 DD&A rate of $1.77 per Mcfe, 19% better than second quarter 2002. The improvement in DD&A is reflective of ATPs growing reserve base and low acquisition and development costs.





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ATP executed a senior credit facility in August 2003
which has an initial borrowing base of $110 million, matures in August 2007, and is secured by substantially all of the Companys Gulf of Mexico assets. The Companys current senior credit facility slated to mature in 2004 with a $50
million borrowing base and secured by substantially the same assets, was repaid in conjunction with this transaction. In addition, the Company used a portion of the availability to retire the entire amount of its outstanding subordinated note which
would have matured in 2005 and carried an interest rate of approximately 16.5%. Through June 30, 2003, ATPs interest cost under those combined agreements was approximately 11.3% on the $81.3 million outstanding ATP collective debt. The overall
interest rate, including associated fees, of the newly executed $110 million senior secured facility is projected to be 8.9%.



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|                                                                  |  | Three Months Ended June 30, |        | Six Months Ended June 30, |  
|----------------------------------------------------------------- |  | --------------------------- | ------ | ------------------------- | -
|                                                                  |  | 2003                        |        | 2002                      |  
|Selected Operating Statistics                                     |  |                             |        |                           |  
|                                                                  |  |                             |        |                          
|Production                                                        |  |                             |        |                           |  
|Natural gas (MMcf)                                                |  |                             | 2,632  |                           |  
|Oil and condensate (MBbls)                                        |  |                             | 322    |                           |  
|                                                                  |  |                             |        |                           |  
|Natural gas equivalents, (MMcfe)                                  |  |                             | 4,564  |                           |  
|                                                                  |  |                             |        |                          
|Average Prices (includes effect of settled derivative activities) |  |                             |        |                           |  
|Natural gas (per Mcf)                                             |  | $                           | 3.33   |                           | $
|Oil and condensate (per Bbl)                                      |  |                             | 26.19  |                           |  
|Natural gas, oil and condensate (per Mcfe)                        |  |                             | 3.77   |                           |  
|Lease operating expense (per Mcfe)                                |  |                             | 0.81   |                           |  
|                                                                  |  |                             |        |                          
|Other Expenses, per Mcfe                                          |  |                             |        |                           |  
|General and administrative                                        |  | $                           | 0.73   |                           | $
|Depreciation, depletion and amortization                          |  |                             | 1.34   |                           |  
|                                                                  |  |                             |        |                          
|Selected Financial Data                                           |  |                             |        |                           |  
|(In Thousands, Except Per Share Data)                             |  |                             |        |                           |  
|Oil and gas revenues, including settled derivatives(1)            |  | $                           | 17,207 |                           |  
|                                                                  |  |                             |        |                          
|Net income (loss)                                                 |  | $                           | 431    |                           | $
|Per share, basic and diluted                                      |  | $                           | 0.02   |                           | $
|Average shares outstandingbasic                                  |  |                             | 22,481 |                           |  
|Average shares outstandingdiluted                                |  |                             | 22,584 |                           |  

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|(1) |  | See oil and gas revenue reconciliation on the last page of this press release.
|--- |  | ------------------------------------------------------------------------------



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Developments and Acquisitions





Gulf of Mexico



During the first half of 2003, ATP brought Eugene Island 71 and West Cameron 101 to production. ATP is the operator and has a 100% working interest in each of these two properties. Development at West Cameron 284
continued throughout the second quarter of 2003 with first production commencing in July 2003. West Cameron 284 was developed by installing a caisson and drilling and completing a horizontal and a vertical well. ATP has a 75% working interest and is
the operator of West Cameron 284.



Company operated developments at Garden
Banks 142/186/187 (Matia/Cabrito) and Ship Shoal 358 are on schedule and should commence production later this year. At Matia/Cabrito, ATP has an 80% working interest, and at Ship Shoal 358, ATP has a 51% working interest. Each property will be
developed with two wells drilled from a platform located on each property. To improve the economics on each development, ATP will recycle and relocate two existing platforms from the Companys Vermilion 410 development, which is simultaneously
being abandoned. A significant component of the platform structure has been installed at each of the respective developments. The relocation of the platform structures is expected to be completed in the third quarter. The Company expects to drill
the four wells in the second half of this year with some well completions possibly extending into the first quarter of next year.



ATP acquired two properties in the Gulf of Mexico in 2003. The first acquisition, West Cameron 663, was acquired at the annual OCS Central Gulf of Mexico Offshore Lease
Sale held March 19, 2003. West Cameron 663 contains proved reserves and is located in approximately 366 feet of water in close proximity to the Companys Matia/Cabrito project. The discovery well on West Cameron 663 was drilled to a depth of
9063 feet in 1985 with proved hydrocarbons at approximately 7800 feet measured depth. ATP operates West Cameron 663 with a 100% working interest. The second acquisition, West Cameron 432, is located in approximately 109 feet of water. ATP expects to
begin development operations on West Cameron 432 in 2004 from an existing platform located on West Cameron 432. ATP operates West Cameron 432 with a 100% working interest.



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U.K. Sector North Sea



The Company announced that its subsidiary, ATP Oil & Gas (UK) Limited (ATP), has been
awarded two licenses in the UKCS 21stLicensing Round. ATP will receive a 100% equity interest and operatorship of
North Sea Blocks 2/10 and 3/11b, which contain the Emerald oil field along with several undeveloped oil and gas discoveries and additional upside potential. ATPs analysis indicates that there may be substantial remaining oil reserves in the
Emerald structure. ATP will also receive a 50% equity interest in North Sea Block 49/30b which includes an undeveloped gas discovery.



The Companys first UK Sector North Sea development, Helvellyn, is expected to commence production in the second half of 2003. We had expected first production in
the second quarter of this year; however, we became aware that certain of the modifications at the host platform were not completed and we encountered further delays in our efforts to commence production. During the second half of 2003, we will
begin a required intervention on the well and the operator of the host platform is expected to complete the necessary modifications on the platform. ATP is the operator and has a 50% working and net revenue interest in Helvellyn.





Capital
Resources and Liquidity



Second quarter 2003 cash flow was used
primarily for previously described development activities and general corporate purposes. During the second quarter 2003, the Company raised $10.9 million (net of offering costs of $0.9 million) through an offering of 4,000,000 shares of common
stock.



During August 2003, ATP replaced its existing senior secured revolving
credit facility with a new $110 million senior credit facility that matures in August 2007. The new facilitys initial borrowing base is $110 million and is secured by substantially the same assets as the Companys existing senior secured
revolving credit facility.



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Conference Call



ATP will host a conference call to discuss second quarter 2003 results on August 15, 2003 at
3:00 p.m. CT. To participate in the live webcast, log on to www.atpog.com ten minutes prior to the start of the call and click on Investor Info/Conference Calls. To listen to the conference call via telephone, contact Isabel Plume at
713-403-5517 for the dial-in number and conference identification number. If you are unable to participate during the live webcast, the call will be archived on our Web site, www.atpog.com, for five business days. A recorded replay can be
accessed 24 hours after the call. The rebroadcast number is 1-800-428-6051 and id code 303279.





About ATP Oil & Gas



ATP Oil & Gas is focused on development and production of natural gas and oil in the Gulf of Mexico and the North Sea. The company trades publicly as ATPG on the
NASDAQ National Market.





Forward-looking Statements



Certain
statements included in this news release are forward-looking statements under the Private Securities Litigation Reform Act of 1995. ATP cautions that assumptions, expectations, projections, intentions, or beliefs about future events may,
and often do, vary from actual results and the differences can be material. Some of the key factors which could cause actual results to vary from those ATP expects include changes in natural gas and oil prices, the timing of planned capital
expenditures, availability of acquisitions, uncertainties in estimating proved reserves and forecasting production results, operational factors affecting the commencement or maintenance of producing wells, the condition of the capital markets
generally, as well as our ability to access them, and uncertainties regarding environmental regulations or litigation and other legal or regulatory developments affecting our business. More information about the risks and uncertainties relating to
ATPs forward-looking statements are found in our SEC filings.



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Balance Sheet

(In Thousands)





|                                                                                                                                                                                                |  | June 30,2003 |          |   | December 31,2002 |  
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |  | ------------ | -------- | - | ---------------- | -
|Assets                                                                                                                                                                                          |  | (unaudited)  |          |   |                  |  
|Current assets                                                                                                                                                                                  |  |              |          |   |                  |  
|Cash and cash equivalents                                                                                                                                                                       |  | $            | 5,536    |   |                  | $
|Restricted cash                                                                                                                                                                                 |  |              |         |   |                  |  
|Accounts receivable (net of allowance of $1,266)                                                                                                                                                |  |              | 27,043   |   |                  |  
|Deferred tax asset                                                                                                                                                                              |  |              | 1,556    |   |                  |  
|Other current assets                                                                                                                                                                            |  |              | 3,388    |   |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Total current assets                                                                                                                                                                            |  |              | 37,523   |   |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Oil and gas properties                                                                                                                                                                          |  |              |          |   |                  |  
|Oil and gas properties (using the successful efforts method of accounting)                                                                                                                      |  |              | 412,313  |   |                  |  
|Less: Accumulated depreciation, depletion, impairment and amortization                                                                                                                          |  |              | (240,955 | ) |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Oil and gas properties, net                                                                                                                                                                     |  |              | 171,358  |   |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Furniture and fixtures (net of accumulated depreciation)                                                                                                                                        |  |              | 770      |   |                  |  
|Deferred tax asset                                                                                                                                                                              |  |              | 20,057   |   |                  |  
|Other assets, net                                                                                                                                                                               |  |              | 2,296    |   |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Total assets                                                                                                                                                                                    |  | $            | 232,004  |   |                  | $
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Liabilities and Shareholders Equity                                                                                                                                                            |  |              |          |   |                  |  
|Current liabilities                                                                                                                                                                             |  |              |          |   |                  |  
|Accounts payable and accruals                                                                                                                                                                   |  | $            | 47,842   |   |                  | $
|Current maturities of long-term debt                                                                                                                                                            |  |              |         |   |                  |  
|Asset retirement obligation                                                                                                                                                                     |  |              | 5,659    |   |                  |  
|Derivative liability                                                                                                                                                                            |  |              | 6,442    |   |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Total current liabilities                                                                                                                                                                       |  |              | 59,943   |   |                  |  
|Long-term debt                                                                                                                                                                                  |  |              | 80,537   |   |                  |  
|Asset retirement obligation                                                                                                                                                                     |  |              | 16,495   |   |                  |  
|Deferred revenue                                                                                                                                                                                |  |              | 1,019    |   |                  |  
|Other long-term liabilities and deferred obligations                                                                                                                                            |  |              | 20,603   |   |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Total liabilities                                                                                                                                                                               |  |              | 178,597  |   |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Shareholders equity                                                                                                                                                                            |  |              |          |   |                  |  
|Preferred stock: $0.001 par value, 10,000,000 shares authorized; none issued                                                                                                                    |  |              |         |   |                  |  
|Common stock: $0.001 par value, 100,000,000 shares authorized; 24,571,196 issued and 24,495,356 outstanding at June 30, 2003;
20,398,007 issued and 20,322,167 outstanding at December 31, 2002 |  |              | 25       |   |                  |  
|Additional paid in capital                                                                                                                                                                      |  |              | 92,214   |   |                  |  
|Accumulated deficit                                                                                                                                                                             |  |              | (36,485  | ) |                  |  
|Accumulated other comprehensive loss                                                                                                                                                            |  |              | (1,436   | ) |                  |  
|Treasury stock                                                                                                                                                                                  |  |              | (911     | ) |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Total shareholders equity                                                                                                                                                                      |  |              | 53,407   |   |                  |  
|                                                                                                                                                                                                |  |              |          |   |                  |  
|Total liabilities and shareholders equity                                                                                                                                                      |  | $            | 232,004  |   |                  | $
|                                                                                                                                                                                                |  |              |          |   |                  |  



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Income Statement

(In Thousands, Except Per Share Amounts)

(Unaudited)





|                                                                                          |  | Three Months EndedJune 30, |        |   | Six Months EndedJune 30, |  
|----------------------------------------------------------------------------------------- |  | -------------------------- | ------ | - | ------------------------ | -
|                                                                                          |  | 2003                       |        |   | 2002                     |  
|Oil and gas revenues                                                                      |  | $                          | 18,627 |   |                          | $
|                                                                                          |  |                            |        |   |                          |  
|Costs and operating expenses:                                                             |  |                            |        |   |                          |  
|Lease operating expenses                                                                  |  |                            | 3,702  |   |                          |  
|Geological and geophysical expenses                                                       |  |                            | 146    |   |                          |  
|General and administrative expenses                                                       |  |                            | 3,351  |   |                          |  
|Non-cash compensation expense (general and administrative)                                |  |                            |       |   |                          |  
|Depreciation, depletion and amortization                                                  |  |                            | 6,095  |   |                          |  
|Accretion expense                                                                         |  |                            | 718    |   |                          |  
|Loss on abandonment                                                                       |  |                            | 2,655  |   |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Total costs and operating expenses                                                        |  |                            | 16,667 |   |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Income from operations                                                                    |  |                            | 1,960  |   |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Other income (expense):                                                                   |  |                            |        |   |                          |  
|Interest income                                                                           |  |                            | 22     |   |                          |  
|Interest expense                                                                          |  |                            | (2,316 | ) |                          |  
|Other                                                                                     |  |                            | 1,119  |   |                          |  
|Loss on derivative instruments                                                            |  |                            | (122   | ) |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Total other income (expense)                                                              |  |                            | (1,297 | ) |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Income (loss) before income taxes and cumulative effect of change in accounting principle |  |                            | 663    |   |                          |  
|Income tax benefit (expense)                                                              |  |                            | (232   | ) |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Income (loss) before cumulative effect of change in accounting principle                  |  |                            | 431    |   |                          |  
|Cumulative effect of change in accounting principle, net of tax                           |  |                            |       |   |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Net income (loss)                                                                         |  | $                          | 431    |   |                          | $
|                                                                                          |  |                            |        |   |                          |  
|Basic and diluted income (loss) per common share:                                         |  |                            |        |   |                          |  
|Income (loss) before cumulative effect of change in accounting principle                  |  | $                          | 0.02   |   |                          | $
|Cumulative effect of change in accounting principle, net of tax                           |  |                            |       |   |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Net income (loss) per common share                                                        |  | $                          | 0.02   |   |                          | $
|                                                                                          |  |                            |        |   |                          |  
|Weighted average number of common shares:                                                 |  |                            |        |   |                          |  
|Basic                                                                                     |  |                            | 22,481 |   |                          |  
|                                                                                          |  |                            |        |   |                          |  
|Diluted                                                                                   |  |                            | 22,584 |   |                          |  
|                                                                                          |  |                            |        |   |                          |  



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Cash Flow Data

(In Thousands)

(Unaudited)



|                                                     |  | Six Months Ended June 30, |        
|---------------------------------------------------- |  | ------------------------- | -------
|                                                     |  | 2003                      |        
|Cash flows from operating activities:                |  |                           |        
|Net income (loss)                                    |  | $                         | 2,829  
|Adjustments to operating activities                  |  |                           | 17,459 
|Changes in assets and liabilities                    |  |                           | 14,157 
|                                                     |  |                           |        
|Net cash provided by operating activities            |  |                           | 34,445 
|                                                     |  |                           |        
|                                                     |  |                          
|Cash flows from investing activities:                |  |                           |        
|Additions and acquisitions of oil and gas properties |  |                           | (40,911
|Additions to furniture and fixtures                  |  |                           | (113   
|                                                     |  |                           |        
|Net cash used in investing activities                |  |                           | (41,024
|                                                     |  |                           |        
|                                                     |  |                          
|Cash flows from financing activities:                |  |                           |        
|Proceeds from issuance of common stock, net          |  |                           | 10,884 
|Payments of long-term debt                           |  |                           | (6,000 
|Deferred financing costs                             |  |                           |       
|Other                                                |  |                           | 287    
|                                                     |  |                           |        
|Net cash provided by (used in) financing activities  |  |                           | 5,171  
|                                                     |  |                           |        
|Increase (decrease) in cash and cash equivalents     |  |                           | (1,408 
|Cash and cash equivalents, beginning of period       |  |                           | 6,944  
|                                                     |  |                           |        
|Cash and cash equivalents, end of period             |  | $                         | 5,536  
|                                                     |  |                           |        



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Hedges, Derivatives and Fixed
Price Contracts

(unaudited)



|Product and Period  |  | As of 8/14/2003(1)
|------------------- |  | ------------------
|                    |  | Volume            
|Gas (MMBtu per day) |  |                   
|3Q03                |  | 32,000            
|4Q03                |  | 27,359            
|                    |  |                   
|1Q04                |  | 16,400            
|2Q04                |  | 13,000            
|3Q04                |  | 13,000            
|4Q04                |  | 13,000            



ATP also entered into a collar for
3,000 MMBtu per day for the first quarter 2004 with a floor of $4.40 and a ceiling of $5.80 per MMBtu that is not reflected above.



|Oil (Bbl per day) |  |       |  |      
|----------------- |  | ----- |  | -----
|3Q03              |  | 1,000 |  | 24.48
|4Q03              |  | 1,000 |  | 24.48



The above are hedges, derivatives and
fixed price contracts in effect at August 14, 2003. Additional hedges, derivatives and fixed price contracts, if any, will be announced during the year.

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|(1) |  | The Company has not entered into any hedges, derivatives, or fixed price contracts since its previous earnings release on May 13, 2003.
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Oil and Gas Revenue Reconciliation(1)

(In Thousands)

(Unaudited)



|                                                                     |  | Period Ending June 30, 2003
|-------------------------------------------------------------------- |  | ---------------------------
|                                                                     |  | Three Months               
|Oil and gas revenues, including the effects of derivative activities |  | $                          
|Hedging ineffectiveness(2)for the period                             |  |                            
|Derivative activities previously recognized in earnings(3)           |  |                            
|                                                                     |  |                            
|Oil and gas revenue per income statement                             |  | $                          
|                                                                     |  |                            

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|(1) |  | Oil and gas revenues including the effects of settled derivative activities differ from our reported revenues from oil and gas production because such numbers omit the effects of
previously recognized changes in the fair market value of derivatives settled during the period. Set forth above is a table reconciling the presented information with revenues from oil and gas production. Oil and gas revenues and oil and gas
revenues including the effects of settled derivative activities are presented because of its acceptance as an indicator of the companys realized cash flow from its oil and gas production during the period for which it is presented.
|--- |  | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|(2) |  | Hedging ineffectiveness is the portion of gains (losses) on derivatives that are based on imperfect correlations to benchmark oil and natural gas prices.
|--- |  | ---------------------------------------------------------------------------------------------------------------------------------------------------------

|(3) |  | Those amounts were previously recognized in income prior to ATPs adoption of hedge accounting in accordance with the provisions of SFAS No. 133, Accounting for
Derivative Instruments and Hedging Activities as amended.
|--- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



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