A group of 303 unrelated Turkish subjects from south-east Anatolia was genotyped for seven NAT2 mutations by polymerase chain reaction-restriction fragment length polymorphism. Genotypes associated with slow acetylation were identified in 57.4% (95%-confidence limits, 51.6%-63.1%). Allele frequencies were NAT2*4 (wild type, 23.1%), *5A (1.3%), *5B (35.6%), *5C (4.8%), *6A (30.5%), *7B (4.5%), and *12A (0.2%). A mutation G191A was not detected. Ambiguous mutation linkages were checked by molecular genetic linkage analysis and DNA sequencing. NAT2-alleles in Turks are similarly distributed as in Middle European ethnicities.