Abstract The release of lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) from rat and mouse hepatocytes was used to rank the in vitro cytotoxic potential of eight chlorinated aliphatic compounds. The rankings were compared with toxicity rankings based on the maximum tolerated doses for each species. Significant correlations between the rankings were obtained when air: water partition coefficients were factored into the in vitro data (EC 50s) in order to adjust for differences in volatility and the retention of the compounds in vivo. For both rats and mice, as an indicator of cytotoxic potency, LDH release correlated better with hydrocarbon toxicity than AST release did. These data support the use of isolated hepatocytes for screening of chemicals for relative toxicity.