QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 11

MARKWEST HYDROCARBON, INC.
COMPUTATION OF EARNINGS PER COMMON SHARE
(in thousands, except per share data)

	Quarter Ended March 31, 2002
Net income	$	175
Weighted average number of outstanding shares of common stock		8,515
Basic earnings per share	$	0.02
Net income	$	175
Weighted average number of outstanding shares of common stock		8,515
Dilutive stock options		13
		8,528
Earnings per share assuming dilution	$	0.02

QuickLinks

EXHIBIT 11

MARKWEST HYDROCARBON, INC. COMPUTATION OF EARNINGS PER COMMON SHARE (in thousands, except per share data)