2,3-Dibromo-1-propanol is a metabolite of the flame retardant tris(2,3-dibromopropyl) phosphate, previously shown to be a mutagen and carcinogen in experimental animals. Toxicology and carcinogenesis studies of 2,3-dibromo-1-propanol were conducted by applying the chemical in 95% ethanol to the interscapular skin of male and female F344/N rats and B6C3F1 mice 5 days a week for 13 weeks in the prechronic study and 48-55 weeks (rats) or 36-42 weeks (mice) in the carcinogenicity study. In the 13-week study, 10 rats and 10 mice of each sex received doses of 0, 44, 88, 177, 375, or 750 mg/kg. Deaths associated with chemical application occurred only in the high-dose (750 mg/kg) male mice. Chemical-related lesions were seen in the kidney of male rats, liver of female rats, and liver and lung of both sexes of mice. Based on the toxicity observed in the 13-week study, 50 rats of each sex received doses of 0, 188, or 375 mg/kg and 50 mice of each sex received 0, 88, or 177 mg/kg in the carcinogenicity study. The planned 2-year study was terminated early because of reduced survival of rats related to chemical-induced neoplasia and because of the appearance of antibodies to lymphocytic choriomeningitis virus in sentinel mice. Nearly all dosed rats had malignant neoplasms at one or more sites, while only one control male and one control female had malignant neoplasms. In rats, neoplasms induced by 2,3-dibromo-1-propanol occurred in the skin, nasal mucosa, Zymbal's gland, oral mucosa, esophagus, forestomach, intestines, liver, kidney, mammary gland (females), clitoral gland (females), spleen (males), and mesothelium (males). In mice, chemical-induced neoplasms occurred in the skin, forestomach, liver (males), and lung (males).