Cystic fibrosis (CF) is the most common autosomal recessive disorder in Caucasian population that involves the lungs, pancreas, sweat glands, intestine, liver and reproductive tract. The majority of men with CF are infertile due to a bilateral congenital absence of the vas deferens (CBAVD). The purpose of the research was to evaluate the occurrence frequency of alleles of CFTR gene in patients with azoospermia. Twenty four men from sterile marriages were examined in whom spermatozoa were not found in 2-3 successive examinations of their semen. In every patient the basic concentration in blood of FSH, LH, PRL and testosterone was determined and ultrasonography of gonads, vas deferens, prostate and spermatic vesicles was performed. The INNO-LIPA CF2 test was used to the screening for the eight most frequently identified mutations in Caucasian population: DF508, G542X, N1303K, 1717-1(G- > A), W1282X, G551D, R553X i DI507. The test is based on the reverse-hybridization method. Carrier-state of one mutated allele was detected in 3 men (12.5% examined causes). In two men DF508 mutation and in one W1282X mutation were detected. The data suggest that the CFTR protein may be involved in the process of spermatogenesis apart from playing a critical role in the development of the vas deferens.