The subchronic toxicity of dimethylformamide (68122) (DMF) was studied in rats and mice. Fischer-344-rats and B6C3F1-mice were exposed to 0, 150, 300, 600, or 1,200 parts per million (ppm) DMF 6 hours daily, 5 days per week for 12 weeks. The animals were observed for overt signs of toxicity. Body weights were monitored. After 60 days of exposure, all survivors were killed and necropsied. Blood was taken for clinical chemistry and hematology analyses. Few overt signs of toxicity were seen. Only three rats died during the study, one 300ppm male and one rat of each sex at 1,200ppm. Eleven mice died or were sacrificed moribund during the study. Most were from the 600 and 1,200ppm groups. Body weights were significantly depressed in males from week 4 on and in females from week 2 on. Dose/related increases in serum cholesterol occurred. There were slight decreases in erythrocyte count, hematocrit, and hemoglobin, and an increase in number of reticulocytes. Treatment related lesions were seen only in the liver. These included yellow/brown pigmented areas, areas of collapse near the central veins, and fibrosis in rats, and yellow/brown pigmentation, hepatic cytomegaly around central veins, and cellular necrosis in mice. No histopathologic changes were seen in rats given 150ppm DMF. The authors conclude that the liver may be the target organ for DMF. The no effect dose is below 150ppm and the maximum tolerated dose is below 600ppm.