Groups of 100 male and 100 female Crl:CDBR rats were exposed by whole-body inhalation to FC-113 (1,1,2-trichloro-1,2,2-trifluoroethane) for 6 hr a day, 5 days a week for 24 months. Average exposure concentrations (+/- 1 SD) were 0.0 (control), 2000 +/- 100, 10,000 +/- 500, and 20,000 +/- 1000 ppm (v/v), respectively. Body weights were consistently lower in both male and female rats in the 20,000 ppm exposure group after approximately 1 and 4 months' exposure, respectively, and in female rats after 12 months' exposure at 10,000 ppm. Observations of appearance and behavior, mortality, and clinical laboratory measurements were unremarkable during the 24-month exposure period. Despite exposure levels as high as 20,000 ppm, only occasional slight increases in urinary fluoride were seen. Microscopic examination of tissues from rats examined during and at the end of the 24-month study revealed no evidence of compound-related toxicity or carcinogenicity. Based mainly on a 5 to 10% decrease in body weight gain at the 10,000 and 20,000 ppm exposure levels, the no-observed-effect level for FC-113 in this study was 2000 ppm.