The potential for behavioral toxicity of the water contaminant chloral (CHL) was ascertained from acute, 14 day and 90 days of exposure in adult mice and perinatal exposure. Acute motor incoordination produced by CHL occurred 5 min after gavage and persisted for about 2hr. The ED50 for acute CHL effects was 84.2mg/kg, a value less than 1/10th of the acute LD50. Exposure for 14 days to either 14.4 or 144.0mg/kg/day of CHL by gavage did not produce any deleterious effects on body weight, behavioral observations, locomotor activity, motor coordination or swimming endurance which were measured 24-48hr after exposure was terminated. Subchronic, 90 day exposure to 0.70 or 0.07mg/ml CHL in drinking water (15.7 and 159.8mg/kg/day) did not affect the palatibility of drinking water since total fluid intakes were not reduced. Mice exposed to these doses of CHL did not gain weight as rapidly as control mice. Exposure to 159.8mg/kg/day produced a decrease in body temperature after 45 days of exposure and a second temperature measurement indicated that mice exposed to both 15.7 and 159.8mg/kg/day were hypothermic on day 91.