This study is a comprehensive, multidisciplinary review of the health and environmental effects of 1,2-dichloroethane. Other pertinent aspects such as production, use, methods of analysis, and regulatory restrictions are also discussed. Approximately 250 references are cited. 1,2-Dichloroethane is manufactured in greater tonnage than any other chlorinated organic compound; in 1977 nearly 5 million metric tons was synthesized in the United States. It is used primarily as a raw material in the production of vinyl chloride monomer and a few other chlorinated organic compounds. The environment is exposed to this chlorinated hydrocarbon primarily through manufacturing losses. Smaller exposures occur through dispersive uses, such as grain fumigations and application of paints and other coatings, and through storage, distribution, and waste disposal operations. Concentrations of 1,2-dichloroethane in environmental air and water distant from point sources are small--on the order of parts per billion or less. Concentrations in the environment near point sources are unknown. 1,2-Dichloroethane is toxic to humans, other vertebrates and invertebrates, plants, and microorganisms. It is an established carcinogen in rats and mice exposed by oral intubation and is a weak mutagen in some bacteria and certain grains.