The pesticide 1,2-dibromo-3-chloropropane (DBCP) is a known male reproductive toxin. Previous studies employed production-grade DBCP containing allyl chloride and epichlorohydrin, both capable of producing effects similar to DBCP. The purpose of this study was to determine if purified DBCP caused the same effects as DBCP containing allyl chloride. Rats were injected for 6 mo with varying doses of pure or production-grade DBCP. Very few differences were observed in the parameters measured between pure and production-grade DBCP-treated animals at any one dose level. Treatment with 25 mg/kg DBCP, pure or production grade, reduced body weight as well as the weight of the testes, prostate glands and seminal vesicles, and elevated serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This dose of pure DBCP reduced serum testosterone. Treatment with 5 mg/kg of either grade DBCP caused decreases only in body and testis weights. Animals treated with 1 mg/kg did not show any major differences from controls. These results indicate that DBCP, and probably not a contaminant, is responsible for the effects observed on male reproduction. Furthermore, DBCP appears to affect either androgen action or production since multiple androgenic indices are affected by DBCP administration.