A high-resolution gas chromatographic method is described which allows the determination of the enantiomeric ratio of a-hexachlorohexane (HCH) in environmental samples within 18 min. A stationary phase with low bleeding was obtained by diluting permethylated heptakis(2,3,6-tri-O-methyl)-~-cyclodextrin in a OH-terminated polysiloxane. It allowed temperature programming with detection in the low-picogram range using electron capture detection and high-resolution mass spectrometry. The separation method is compatible with standard sample cleanup procedures, which facilitate the reanalysis of stored sample extracts. Detailed information is given about the preparation of the separation capillary, the analytical parameters, and the reproducibility of the quantification. Furthermore, the applicability of the method to different environmental samples is demonstrated. First results, which showed an excess of a(+)-HCH in all analyzed sample matrices, are discussed.