The subchronic renal and hepatotoxicities of five selected halomethanes, which are drinking water contaminants, were evaluated following a 14-day exposure period. Bromodichloromethane, bromoform, chloroform, dibromochloromethane and methylene chloride were administered at three dose levels. Toxicity was evaluated by measuring increases in total body weight, active uptake of p-aminohippuric acid into renal cortical slices, blood urea nitrogen, serum creatinine and serum glutamate--pyruvate transaminase levels and by performing a histopathologic examination of liver and kidney tissues. At the dose level employed in these experiments, dose-related effects on the liver and kidney were seen with the uptake of p-aminohippuric acid into kidney slices and with the histopathologic evaluation of tissues. The other parameters revealed adverse renal and hepatic effects in only the high dose groups. Treatment-related effects seen in the methylene chloride exposed mice were less pronounced than in the other halomethane treatment groups. In general, histopathological changes were the most sensitive indicators of both liver and kidney damage.