Chlorinated compounds in fish lipids [determined by neutron activation analysis as extractable, organically bound chlorine (EOCl)] were characterized by liquid-liquid extractions after enzymatic hydrolysis and after forming fatty acid methyl esters (FAMEs). Most of the chlorinated compounds in lipids from four different fish samples could be hydrolysed. Comparison with results of methanolysis of two of the fish lipids indicated that chlorinated fatty acids made up the major portion of EOCl. Using gas chromatography (GC) with electrolytic conductivity detection (ELCD), chlorinated compounds were found among FAMEs of eel lipids containing 1200 ppm of EOCl. Approximately 90% of EOCl was detected by GC-ELCD. The GC-detectable compounds are suggested to be methyl esters of chlorinated fatty acids and 9,10-dichlorostearic acid was tentatively identified after co-injection of the synthesized compound.