An eaperiment on the degradation of γ-BHC (r-hegachlorocyclohezane) by microbial populations was carried out using soil samples from orchards and wheat fields in which BHC applied for many years.It was found that γ-BHC in soils could be degraded more rapidly by soil microbes under the optimum temperature and adequate soil moisture conditions.All of the γ-BHC added in soil (700μg/lOg soil) were completely degraded within 56 days under favorable moisture conditions.Microorganisms being able to use γ-BHC as their sole carbon source for growth were isolated and counted on a selected medium.It was shown that both in shaking culture and sterilized soil enlture γ-BHC was degraded obviously by Flavobacterium sp.350^#,Agrobacteriumsp.70^# and Alcaligenes sp 670^#.63.1% of the γ-BHC applied were degraded by Flavobacterium sp.350^# within 84 days.It was noticed that the microbes did not transform the γ-BHC into β-BHC which is more harmful to human being either in soil culture or in pure culture.