Glutathione S-transferases (GSTs) belong to a family of detoxification enzymes that conjugate glutathione to various xenobiotics, thus facilitating their expulsion from the cell. GST activity is elevated in many insecticide-resistant insects, including the DDT-resistant malaria vector Anopheles gambiae. Crystals of the recombinant form of a GST from A. gambiae, agGST1-6, have been grown in at least five different crystal forms, with a broad range of diffraction resolution limits. A complete 2.0 A data set has been collected on a C-centered orthorhombic crystal form with unit-cell parameters a = 99.0, b = 199.4, c = 89.6 A. A search for heavy-atom derivatives has been initiated, along with phase-determination efforts by molecular replacement.