Exhibit 21

SUBSIDIARIES

OF

CHESAPEAKE ENERGY CORPORATION*

Oklahoma Corporation

CorporationsState of Organization

Chesapeake E&P Holding Corporation    Oklahoma

Chesapeake Energy Louisiana Corporation    Oklahoma

Chesapeake Energy Marketing, Inc.    Oklahoma

Chesapeake Operating, Inc.    Oklahoma

CHK Energy Holdings, Inc.    Texas

Limited Liability CompaniesState of Formation

Chesapeake Appalachia, L.L.C.    Oklahoma

Chesapeake Exploration, L.L.C.    Oklahoma

Chesapeake Land Development Company, L.L.C.    Oklahoma

Chesapeake Midstream Development, L.L.C.    Oklahoma

Chesapeake Oilfield Operating, L.L.C.    Oklahoma

CHK Cleveland Tonkawa, L.L.C.Delaware

CHK Utica, L.L.C.Delaware

COS Holdings, L.L.C.    Oklahoma

MidCon Compression, L.L.C.    Oklahoma

Nomac Drilling, L.L.C.    Oklahoma

Partnerships

Chesapeake Louisiana, L.P.    Oklahoma

* In accordance with Regulation S-K Item 601(b)(21), the names of particular subsidiaries that, considered in the aggregate as a single subsidiary, would not constitute a significant subsidiary (as that term is defined in Rule 1-02(w) of Regulation S-X) as of the end of the year covered by this report have been omitted.