In this investigation it is demonstrated that the half-lives of the insecticide lindane (gamma-HCH) in mussels and different fish species are dependent on their lipid content. It is found that the bioconcentration factors on a wet weight basis (BCF-w) of gamma-HCH in different aquatic organisms such as mussels, Daphnia, and fishes range from 43 to 4240. It is further demonstrated that the bioconcentration factors on a wet weight basis are positively correlated with the lipid content (%). The mean bioconcentration factor on a lipid basis (BCF-L) of gamma-HCH is 11,000. This BCF-L value is in satisfactory agreement with the log K-ow value of lindane (4.10).