MarkWest Announces First Annual Investor Conference

DENVER, June 20  /PRNewswire-FirstCall/ -- MarkWest Energy Partners, L.P. (AMEX:MWE) and MarkWest Hydrocarbon, Inc. (AMEX:MWP), today announced that they will conduct their first annual investor conference in mid-September of 2006, with details to follow.  Originally the investor conference was planned for June.  Due to the anticipated timing of our previously announced capital markets activities, we have chosen to delay this event.  Initial response to the conference is extremely positive and as a result a session in Houston has been added to the originally scheduled New York session.

MarkWest Hydrocarbon, Inc. (AMEX:MWP) controls and operates MarkWest Energy Partners, L.P. (AMEX:MWE), a publicly-traded limited partnership engaged in the gathering, processing and transmission of natural gas; the transportation, fractionation and storage of natural gas liquids; and the gathering and transportation of crude oil.  We also market natural gas and NGLs.

MarkWest Energy Partners, L.P. is a publicly traded master limited partnership with a solid core of midstream assets and a growing core of gas transmission assets.  It is the largest processor of natural gas in the Northeast and is the largest gas gatherer of natural gas in the prolific Carthage field in east Texas.  It also has a growing number of other gas gathering and intrastate gas transmission assets in the Southwest, primarily in Texas and Oklahoma.

This press release includes "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.  All statements other than statements of historical facts included or incorporated herein may constitute forward-looking statements.  Although we believe that the expectations reflected in the forward-looking statements are reasonable, we can give no assurance that such expectations will prove to be correct.  The forward-looking statements involve risks and uncertainties that affect our operations, financial performance and other factors as discussed in our filings with the Securities and Exchange Commission.  Among the factors that could cause results to differ materially are those risks discussed in our Form 10-K for the year ended December 31, 2004, and our Forms 10-Q, as filed with the SEC. 

DATASOURCE: MarkWest Energy Partners, L.P.



CONTACT:  Frank Semple, President & CEO, or Jim Ivey, CFO, or Andy

Schroeder, VP and Treasurer, all of MarkWest Energy Partners, L.P.,

[phone], 



Web site:  http://www.markwest.com/

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