k1. The alpha-isomer of 1,2,3,4,5,6-hexachlorocyclohexane (HCH) is converted in rats to 1,2,4-trichlorobenzene, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, other trichlorophenols, and 2,3,4,6-tetrachlorophenol, which were excreted in urine. 2. Alpha-HCH is also converted to 3,4,6/5-pentachlorocyclohexene which is detectable in kidneys, but not in urine. 3. The results of this study are discussed with references to earlier work and to gamma-HCH metabolism.