This study determined the genotypes of the CYP2A6 gene in 96 smokers and 141 non-smokers in a Japanese population. The frequencies of wild-type of the CYP2A6* 1 and those with a whole deletion of the CYP2A6 gene were 93 (96.9%) and 3 (3.1%) in 96 smokers, and 134 (95.0%) and 7 (5.0%) in non-smokers, respectively. In addition, neither the CYP2A6* 2 nor CYP2A6* 3 alleles were observed in the population studied. There were no significant differences in the CYP2A6 genotype frequencies between smokers and non-smokers, as well as in the number of cigarettes smoked and the nicotine amounts inhaled per day between the CYP2A6* 1 and the deletion of CYP2A6. These results suggest that either the deletion or non-deletion of the CYP2A6 gene shows no significant effect on smoking behavior for the Japanese population examined.