SecProbe.io

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								October 7, 2005

Mr. James G. Ivey
Chief Financial Officer
Markwest Energy Partners, L.P.
155 Inverness Drive West, Suite 200
Englewood, CO 80112-5000

	Re:	Markwest Energy Partners, L.P.
		Form 10-K for Fiscal Year Ended December 31, 2004
Filed June 24, 2005
Form 10-Q for Fiscal Quarters Ended March 31, 2005 and June 30,
2005
Filed June 24, 2005 and August 9, 2005
Response Letter Dated September 15, 2005
		File No. 0-21956

Dear Mr. James G. Ivey:

      We have reviewed your filings and response letter and have
the
following comments.  We have limited our review of your filing to
those issues we have addressed in our comments Where indicated, we
think you should revise your document in response to these
comments.
If you disagree, we will consider your explanation as to why our
comment is inapplicable or a revision is unnecessary.  Please be
as
detailed as necessary in your explanation.  In some of our
comments,
we may ask you to provide us with information so we may better
understand your disclosure.  After reviewing this information, we
may
raise additional comments.

Form 10-K for the Fiscal Year Ended December 31, 2004

Overview of the Industry and Our Business, page 9

1. We note your response to prior comment one indicating that your
gross margin measure excludes costs, such as depreciation and
amortization, typically attributable to gross margin measures
presented under GAAP.  Therefore, it appears that this measure is
a
non-GAAP financial measure. As such, we believe you will need to
remove this measure or change its title so it is not confused with
gross margin as calculated on a GAAP basis.  In the event you
modify
the title of this measure, please provide reconciliation to the
most
directly comparable financial measure calculated and presented in
accordance with GAAP and all other disclosures required by Item
10(e)
of Regulation S-K.

Financial Statements

Note 2, Summary of Significant Accounting Policies, page 72

Basis of Presentation, page 72

2. We have reviewed your response to prior comment number two and
your proposed disclosure.  Please expand your accounting policy
with
respect to equity method investments to disclose how you evaluate
and
measure your equity method investments for impairment.  Refer to
APBO
No 18.

Note 6, Intangible Assets Subject to Amortization, page 82

3. We note that your response to prior comment six indicated that
your customer contracts have lives of 5 to 10 years with an
automatic
one year extension. Please tell us what evidence you have
regarding
historical renewals with these customers, if any. Additionally
clarify whether there is any agreement or clause in the existing
contracts supporting renewal beyond the automatic one year
extension.
Submit to us a schedule showing each customer, the contractual
term,
renewal right and a brief description of the history you have of
renewing contracts with each of your customers.

Note 13, Commitments and Contingencies, page 91

4. We note your response to prior comment seven in which you
indicate
that your insurance carrier has settled claims to date related to
the
pipeline leak, although your disclosures in your 10-Q for the
fiscal
quarter ended June 30, 2005, on page 39, indicate that claims
related
to the leak have been denied.  Please clarify and reconcile these
statements which seem to conflict. Demonstrate how it is
appropriate
to determine that your liability is remote when the insurance
company
has denied your claims. We continue to believe that you will need
to
expand your disclosure in your Form 10-K to correspond with those
of
your Form 10-Q since those filings were made contemporaneously.
Finally, as previously requested, please expand your disclosures
to
indicate the likelihood of your loss exposure as probable,
reasonably
possible or remote, along with an estimate range of loss in the
event
you determine the likelihood to be reasonably possible.  Refer to
SFAS 5.

Closing Comments

	As appropriate, please amend your filing and respond to these
comments within 10 business days or tell us when you will provide
us
with a response.  You may wish to provide us with marked copies of
the amendment to expedite our review.  Please furnish a cover
letter
with your amendment that keys your responses to our comments and
provides any requested information.  Detailed cover letters
greatly
facilitate our review.  Please understand that we may have
additional
comments after reviewing your amendment and responses to our
comments.

	You may contact Jonathan Duersch at (202) 551-3719 if you
have
questions regarding comments on the financial statements and
related
matters.  Please contact me at (202) 551-3683 with any other
questions.

								Sincerely,

								Jill Davis
								Branch Chief

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Mr. James G. Ivey
Markwest Energy Partners, L.P
October 7, 2005
page 1

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-0405

   DIVISION OF
CORPORATION FINANCE
MAIL STOP 04-05

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