Because of the recent increase in exposure of individuals to potentially harmful chemicals, it has become increasingly important to test the potential of environmental chemicals to cause adverse reproductive effects. The Division of Toxicology within the Department of Pharmacology, Medical College of Virginia has responded to this need by examining the abilities of Kepone, hexachlorobenzene, 2,4-dinitrotoluene, 1,2,3,4-tetrabromobutane, chloral hydrate, 1,1,2-trichloroethylene, 1,2-dichloroethylene, 1,2-dichloroethane, dibromochloromethane, trichloromethane, and 1,1,1-trichloroethane to elicit harmful reproductive effects. The following tests were used to assess the extent of these effects: analysis of effects upon rat ejaculate volume and sperm morphology, distribution studies in rats, determination of the cellular sites of action in a P388D1 lymphoid neoplasm cell line, performance of a multi-generation murine experiment which included dominant lethal and teratologic studies, and analysis of the inhibition of mouse testicular DNA synthesis.