The inhibitors of the phosphodiesterase type 5 (iPDE-5) are today the first line agents for the therapy of the erectile dysfunction (ED). The data regarding their effect on the male fertility is controversial.

We have analyzed the influence of the iFDE-5 on the spermatogenesis in rats. 45 rats were included into the experiment. They were divided by 4 main groups and 1 control group. Into the control group 5 rats on a standard diet were included. In each of 4 experimental groups were 10 rats, which were standard fed with the inclusion of the iFDE-5 (sildenafil, tadalafil, vardenafil, udenafil).

In the beginning of the experiment in all rats a median laparotomy with subsequent one-side orchiectomy was made. Next to the operation all the rats received the iPDE-5 according to the randomization plan. In all the rats by the end of the 71st day of the beginning of the experiment orchiectomy on the contralateral side was performed with subsequent histological analysis of the testicular tissues. Morphological investigation showed, that spermatogenesis index was insignificantly lower in the group of rats, who received vardenafil, and it was shown, that this index was significantly lower in the rats of udenafil group. In the sildenafil and tadalafil groups no changes of the index