Institute of molecular biology and genetics NAS of Ukraine, Kyiv; 150 Zabolotnogo str., Kyiv, 03680, Ukraine olga_fesay@ukr.netAnalysis of microdeletions on the long arm of the human Y chromosome, that are associated with spermatogenic failure, allowed us to define three regions of Yq (AZFa, AZFb and AZFc) recurrently deleted in infertile males. Microdeletions were detected in 16 of total 355 (4,5%) infertile men. Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which also involved in male infertility, were detected in 22 out of 355 analyzed infertile men. The most common mutation was F508del (17 of total 22 mutations). 5T allele of CFTR gene associated with congenital bilateral absence of the vas deferens was detected in 16 of total 355 (4,5%) patients. Molecular-genetic analysis of the Y-chromosome microdeletions and CFTR gene mutations as well as genetic counseling are necessary conditions for the diagnostics of patients with male infertility, especially if they are involved in an assisted reproductive technology program.