Cytochrome P450 monooxygenases catalyze the metabolism of approximately 40-60% of widely used drugs with a A6986G CYP3A5 polymorphism determining expresser (A6986, *1) and reduced- expresser (*3) variants with modified drug metabolism activity. In this report, the allele frequency of CYP3A5 *1 and *3 (A6986 or G6986, respectively) was analyzed by the PCR-RFLP technique in a cohort of 200 Polish newborns from the West Pomeranian region. Of the studied group, 1% (n = 2/200) proved homozygous for the CYP3A5*1 allele, 89% (n = 178/200) for the *3 allele, and 10% (n = 20/200) were heterozygous for *1/*3. Similar frequencies were found in other Caucasian European populations. This study provides basic genetic data related to the metabolism of drugs, with a narrow therapeutic window in a Polish population.