Chronic inhalation toxicity and oncogenicity were evaluated in groups of male and female B6C3F1 mice (80/sex/group) receiving whole body exposure to 1,1,1-trichloroethane in an inhalation chamber at nominal concentrations of 0, 150, 500 or 1500 ppm for 6 hrs/day, 5 days/week for 2 years. There were no statistically significant differences in survivability of any exposed groups of mice when compared to their respective controls. In male mice exposed to 500 ppm there was a statistically significant incidence of cystitis and dilatation of the renal pelvis, and inflammatory and obstructive processes involving the genitourinary tract.No tumors in female mice were identified as being statistically significantly increased. A statistically significant decrease in the total number of benign tumors in the 1500 ppm male mice group was observed. Parameters of hematology, clinical chemistry, final body weights, and absolute organ weights for male and female mice were unaffected by the treatment.