MWP Markwest Hydrocarbon,

MarkWest Announces Retirement of Don Heppermann as CFO and His Appointment As Chairman of Finance Committees DENVER, Feb. 20 /PRNewswire-FirstCall/ -- MarkWest Hydrocarbon, Inc. , Frank Semple, President and Chief Executive Officer, announced today that Donald C. Heppermann has given notice of his intention to retire as Chief Financial Officer of MarkWest Hydrocarbon, Inc. and MarkWest Energy General Partners, L.L.C. effective March 1, 2004. Mr. Heppermann will continue to serve on the boards of MarkWest Hydrocarbon and MarkWest Energy Partners, L.P. and will continue active involvement in the financial affairs of the two organizations as Chairman of the Finance Committee for both boards. Also, Mr. Heppermann will continue to advise on strategic initiatives. In commenting on Don's retirement, Frank Semple said, "Don did MarkWest a great favor by coming out of retirement in November 2002 to serve as CFO. In his new role, MarkWest will continue to have the benefit of his advice and counsel while providing him the flexibility he desires for his personal business and family interests." Ted Smith, VP and Controller, will be recommended for election to Chief Accounting Officer for both organizations. Andy Schroeder, VP and Treasurer will assume the responsibility of Investor Relations. Both positions will report to Frank Semple with oversight from Mr. Heppermann as Chairman of the board Finance Committees. MarkWest Hydrocarbon, Inc. (AMEX:MWP), owns and controls the general partner of, and owns a 35% limited partner interest in, MarkWest Energy Partners, L.P. (AMEX:MWE). MarkWest Energy Partners, L.P. is engaged in the gathering, transmission, processing, fractionation and marketing of hydrocarbons. MarkWest Hydrocarbon, Inc. is also engaged in the marketing of natural gas and natural gas liquids. DATASOURCE: MarkWest Hydrocarbon, Inc. CONTACT: Frank Semple, President & CEO, Donald Heppermann, Exec. VP and CFO, both of MarkWest Hydrocarbon, Inc., +1-303-290-8700, Web site: http://www.markwest.com/

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