The human N-acetylation polymorphism, encoded by the NAT2 gene locus, has been associated with higher incidence and/or severity to the adverse effects of therapeutic drugs, and to the carcinogenic actions of environmental and occupational chemicals. In this paper, we describe an efficient method of restriction fragment-length polymorphism and allele-specific amplification analysis which distinguishes between each of 15 (NAT2*4, *5A, *5B, *5C, *6A, *6B, *7A, *7B, *12A, *12B, *13, *14A, *14B, *17, *18) NAT2 alleles that have been identified in human populations. The method should have broad applicability to improvement of drug therapy and to molecular epidemiology investigations of genetic predisposition to cancer and other diseases.