Abstract Emulphor, ethanol, and dimethyl sulfoxide (DMSO) were evaluated as vehicles in studying the toxicity of CCl 4 and CHCl 3 in isolated hepatocytes. The appropriateness of the vehicle was determined by evaluating the following parameters: solubility of CCl 4 and CHCl 3 in the vehicle, cell injury (intracellular K +), cell death (LDH leakage), and lack of interaction (protection or enhanced toxicity) with CCl 4 and CHCl 3. The relative toxicity of the vehicles according to maximum no effect levels ( v v ) was: emulphor (0.125%) > ethanol (1.0%) > DMSO (5.0%). Emulphor at toxic levels was inadequate to dissolve enough CCl 4 to evaluate in this system. Ethanol (5.0, 2.5, 1.0, 0.5%) was more toxic than DMSO and interacted with both CCl 4 and CHCl 3 to enhance toxicity. DMSO (15.0, 5.0, 2.5%) did not significantly alter the toxicity of CCl 4 and CHCl 3; no interaction. These data suggest that DMSO should be the vehicle for evaluating the toxicity of CCl 4 and CHCl 3 and their mechanisms of action in the isolated hepatocyte.