The number of CAG repeats of exon 1 of AR gene was determined in a group of 228 infertile males with azoospermia (n = 68) and oligozoospermia (n = 160) as well as in control group (124 proven fathers) by fluorescent polymerase chain reaction amplification followed by fragment analysis on automated fluorescent analyzer "A.L.F-express". The frequency of alleles with GAG-repeats < or = 18 was significantly higher (P < 0,01) in the group of patients with azoospermia (17,7%) comparing with the control group (2,4%) as well as in the group of patients with oligozoospermia (12,5%) comparing with the control group (2,4%). The frequency of alleles with CAG-repeats > or = 28 significantly differed (P < 0,01) between the group of patients with oligozoospermia (12,5%) and the control group (2,4%). Our data suggest an association between CAG repeats number and impaired spermatogenesis in azoospermic and oligozoospermic males.