The effects of dichloromethane (DCM) on carbon tetrachloride (CT) toxicity were examined in adult male rats. A concomitant treatment of rats with DCM (0.3, 0.6, 1.2 g/kg, po) significantly potentiated the hepatotoxicity of CT (1.0 g/kg, po) as determined by increase in serum GPT (glutamic pyruvic transaminase), GOT (glutamic oxaloacetic transaminase), and SDH (sorbitol dehydrogenase) activity 24 hr following the treatments. Serum LDH (lactate dehydrogenase) activity was increased by either DCM or CT treatment.