The frequency of 29A and 29B mutations in the CYP2D6 gene, the most common mutations among Caucasoid PM (debrisoquine 4-hydroxylase defficient) individuals, has been analyzed in the Russian population. For the detection of the 29A mutation, a new one-step ARMS PCR approach has been developed. The frequency of the 29B mutant allele in Russians appeared to be significantly lower than in other Caucasoid populations, and this observation can be explained by the mixed origin of the population inhabiting Russia. Comparative analysis of the mutation frequencies among individuals of various ages showed no age-related differences.