Finding that estrogen plays an important role in bone homeostasis in men prompted research on relationship of polymorphism at the CYP19 gene and the bone mass. Therefore, influence of 3-bp deletion/insertion polymorphism of CYP19 (TTTA)7 allele on the peak bone mass attainment in males was studied. Fifty-eight unrelated male participants, aged 21-35, were selected depending on the presence of (TTTA)7 (no.=19) or (TTTA)7-3 (no.=39) alleles from the initial cohort of 92 young males. Heterozygotes (TTTA)7/(TTTA)7-3 (no.=13) were not included in the analysis. Serum levels of estradiol, free testosterone, 25-hydroxyvitamin D, bone alkaline phosphatase, osteocalcin, and beta-crosslaps were measured. Bone mass was measured by DXA at the hip and at the spine. (TTTA)7-3 allele was associated with significantly lower femoral neck bone mineral density (BMD) (p=0.02). Logistic regression model indicated strong association of (TTTA)7-3 allele with low BMD in the range of osteopenia/osteoporosis (p=0.014, odds ratio 12.36, confidence intervals 1.65-92.46). In the present study association of 3-bp deletion polymorphism of the (TTTA)7 allele with decreased peak bone mass in males is reported for the first time. However, further studies are necessary to elucidate the functional relevance of this polymorphism.