The investigation was conducted to characterize the acute, subacute and subchronic toxic potency of ingested carbon tetrachloride (CCl4). In the first acute and subchronic toxicity study, male Sprague-Dawley rats of 300-350 g were gavaged with 0, 20, 40 or 80 mg CCl4/kg once daily for 5 consecutive days, rested for 2 days, and dosed once daily for 4 additional days. Rats of 200-250 g were gavaged with 0, 20, 80 or 160 mg CCl4/kg according to the same dosage regimen in the second acute and subacute study. In the first and second studies one group of rats at each dosage-level was sacrificed for clinical chemistry and histopathological evaluation at 24 hr, 4 days and 11 days after initiation of dosing. Single 20 and 40 mg/kg doses had no apparent toxic effect at 24 hr, though 80 mg/kg caused mild hepatic centrilobular vacuolization and significant increases in some serum enzyme levels. In general, there was progressively severe hepatic injury at each dosage-level over the 11-day period.