Four consecutive intraperitoneal (i.p.) injections with 40 mg/kg of 1,2-dibromo-3-chloropropane (DBCP) reduced the in vitro accumulation of p-aminohippurate (PAH) and tetraethylammonium (TEA) by slices of renal cortex and increased blood urea nitrogen (BUN) concentration in both male and female rats, but elevated serum glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) activities in females only. Four consecutive treatments with 1,2-dibromoethane (EDB) reduced the accumulation of PAH in male rats, but failed to alter TEA accumulation, BUN concentration or GPT and GOT activities in rats of either sex. Single i.p. injections of EDB or DBCP (40 mg/kg, approximately one-half of the acute, i.p. LD50 values) were without effect on serum GPT and GOT activities, BUN concentration or the accumulations of PAH and TEA in male rats when measured 24, 48 or 96 h after treatment, except that PAH accumulation was reduced at 96 h. These results indicate that BUN and the accumulations in vitro of PAH and TEA by renal cortical slices are appropriate endpoints for studying DBCP nephrotoxicity. Measurements of serum GOT and GPT activities detected DBCP hepatotoxicity in female rats only. The nephrotoxicity of EDB was indicated by measurement of TEA accumulation only.