EXHIBIT 21 EXHIBIT 21 Upon consummation of the offering, the subsidiaries of the Company will be as follows: SUBSIDIARIES OF PETROGLYPH ENERGY, INC. --------------------------------------- Petroglyph Operating Company, Inc., a Kansas corporation PGP II, L.P., a Delaware limited partnership Spanish Peaks Gathering, L.L.C., a Colorado limited liability company Petroglyph Energy, Inc., a Kansas corporation Petroglyph Gas Partners, L.P., a Delaware limited partnership