Although chloramines have been used to disinfect drinking water in the United States for more than 60 years, interest in these disinfectants has recently increased with the discovery that much lower levels of halogenated organics are produced during chloramination than during chlorination. Considerable controversy exists, however, regarding the effectiveness of chloramines as microbicidal agents and their possible effects on human health. This article reviews the advantages and disadvantages of the use of chloramines in disinfection, including their chemical properties; their effectiveness against bacteria, viruses, and protozoa; and the toxic effects they produce in humans and wildlife. The use of laboratory findings for predicting the efficiency of chloramines in the field is also addressed. Includes 208 references, tables, figures.