EXHIBIT 5 (Vastar Logo) Vastar Resources, Inc. Legal and Government Relations Department 15375 Memorial Drive Houston, Texas 77079 (281) 584-6027 (281) 584-3492 Fax Albert D. Hoppe Vice President, General Counsel and Secretary December __, 1999 Board of Directors Vastar Resources, Inc. 15375 Memorial Drive Houston, Texas 77079 OPINION OF COUNSEL I am Vice President, General Counsel and Secretary of Vastar Resources, Inc. (the "Company") and have acted as counsel for the Company in connection with its Registration Statement on Form S-8 (the "Registration Statement") relating to the registration under the Securities Act of 1933, as amended, of 438,852 shares of the Company's common stock, $0.01 par value (the "Common Stock") (this number includes 33,746, 95,343 and 49,763 shares of Common Stock that were registered in connection with the Vastar Resources, Inc. Savings Plan, the Vastar Resources, Inc. Savings Plan II and the Vastar Resources, Inc. Capital Accumulation Plan, respectively, on Registration Statement Nos. 33-80846, 33-80844 and 33-80848, respectively, that are carried forward to and deemed covered by the Registration Statement) issuable pursuant to the Vastar Resources, Inc. Capital Accumulation Plan, as amended to date and formerly called the Vastar Resources, Inc. Capital Accumulation Plan II (the "Plan"). As the basis for the opinion hereinafter expressed, I have examined such statutes, regulations, records and documents, certificates of corporate and public officials and other instruments as I have deemed necessary or advisable for the purposes of this opinion. In such examination, I have assumed the authenticity of all documents submitted to me as originals and the conformity with the original documents of all documents submitted to me as copies. Based on the foregoing, certain consultations with officers, employees and agents of the Company and on such legal considerations as I deem relevant, I am of the opinion that the shares of Common Stock to be issued by the Company pursuant to the Plan, when issued in accordance with the terms of the Plan, will be validly issued, fully paid and nonassessable. I am a member of the Bars of the States of Colorado, Missouri and Texas and I am familiar with the general corporation law of the State of Delaware and the federal laws of the United States, insofar as necessary for purposes of rendering this opinion. I hereby consent to the use of this opinion as an exhibit to the Registration Statement. Very truly yours, /s/ Albert D. Hoppe