Residues of endosulfan insecticide (α-and β-isomers, and endosulfan sulphate) were determined in the livers of catfish from a cotton growing area during the summer and winter of 1988. The concentration of total endosulfan residues found in the fish was up to 0.31 mg kg(-1) wet wt. It decreased in winter with a maximum 0.02 mg kg(-1) wet wt. The difference in endosulfan residues between seasons was statistically significant (ANOVA,p<0.01).