Of 147 microorganisms isolated from a loamy sand, 71 showed good growth with lindane (gamma-1,2,3,4,5,6-hexachlorocyclohexane) and produced chloride in an aqueous medium. Thirteen soil microorganisms were selected to study the utilization of lindane. Lindane was metabolized by the microbes to gamma-2,3,4,5,6-pentachloro-1-cyclohexene (gamma-PCCH), alpha-3,4,5,6-tetrachloro-1-cyclohexene (alpha-TCCH), beta3,4,5,6-tetrachloro-1-cyclohexene (beta-TCCH), gamma-3,4,5,6-tetrachloro-1-cyclohexene (gamma-TCCH), and pentachlorobenzene (PCB). Cells of Pseudomonas sp. No. 62 grown on lindane simultaneously adapted to gamma-PCCH, alpha-TCCH, beta-TCCH, gamma-TCCH, PCB, 1,2,3,4,-tetrachlorobenzene (1,2,3,4-TCB) and 1,2,4,5-tetrachlorobenzene (1,2,4,5-TCB). The bacteria degraded each of these chemicals at least partially as indicated by an increased rate of oxygen consumption.