Introduction. Cystic fibrosis (CF) is common monogenic disease resulted from CFTR gene mutations. A most of CF male patients are infertile due to the obstructive azoospermia, however, the mechanisms of the reduced fertility in male patients without the obstruction of seminal ducts, also as the influence of CFTR genotype on their development is understudied.Objectiveis to assess an influence the effect of CFTR genotype, clinical form of CF and age on men reproductive system organs, fertility, and testosterone level and semen parameters in male patients with CF. Materials and methods. We examined 71 Russian men (17–39 years old, mean 24.9 ± 5.3) with CF (pancreatic-sufficient, n = 34, and pancreatic-insufficient, n = 37). Clinical, andrology, laboratory and instrumental examination, including scrotal ultrasonography, biochemical semen, and hormonal analyses were performed.Results. Testicular hypoplasia was reveled in 40,5 % CF patients. Diffuse alterations of epididymis, of epididymal and/or testicular cysts were detected in 62 % patients; 10 % of the patients presented symptoms of hypogonadism. As many as 88 % patients showed spermiological signs of bilateral obstruction of seminal ducts at the level of the vas deferens and epididymis, aplasia of the seminal vesicles (azoospermia, oligospermia, low pH and fructose level of the ejaculate). Pancreatic-insufficient CF is an unfavorable prognostic sign for the obstruction of vas deferens, morphological changes in the scrotum. Patients until 25 years (23 %) as 3849+10kb C>T mutation’s carriers (72 %) significantly more frequently presented preserved vas deferens.Conclusion. Pancreatic-sufficient CF, young age and 3849+10kbС>T mutation are favorable factors presented preserved vas deferens and the possible fertility in men with CF.