EXHIBIT 21 SIGNIFICANT SUBSIDIARIES OF CENTERPOINT ENERGY, INC. The following subsidiaries are deemed "significant subsidiaries" pursuant to Item 601(b) (21) of Regulation S-K: Utility Holdings, LLC, a Texas corporation and a direct wholly owned subsidiary of CenterPoint Energy, Inc. CNP Investment Management, Inc., a Texas corporation and a direct wholly owned subsidiary of CenterPoint Energy, Inc. CenterPoint Energy Resources Corp., a Delaware corporation and an indirect wholly owned subsidiary of CenterPoint Energy, Inc. CenterPoint Energy Houston Electric, LLC, a Texas corporation and an indirect wholly owned subsidiary of CenterPoint Energy, Inc. (1) Pursuant to Item 601(b) (21) of Regulation S-K, registrant has omitted the names of subsidiaries, which considered in the aggregate as a single subsidiary, would not constitute a "significant subsidiary" (as defined under Rule 1-02(w) of Regulation S-X) as of December 31, 2004. (2) CenterPoint Energy Resources Corp. also conducts business under the names of its three unincorporated divisions: CenterPoint Energy Arkla, CenterPoint Energy Entex and CenterPoint Energy Minnegasco.