The paper presents the results of the morphological examination of tests of the Wistar rats flown for 22 days onboard the biosatellite Cosmos-605. Histological, histochemical, electron microscopic and biometric investigations of sex glands carried out 24-48 hours and 26-27 days postflight show that an exposure of the rats to weightlessness and other space flight factors induced no morphological changes in the spermatogenic tissue or disorders in the spermatogenic process of the rats. The offspring of male rats that were exposed to 22-day weightlessness did not differ from the controls with respect to the number of the newborns, their weight at birth, weight gain during the first postnatal month, resistance to hypoxia, etc.