The research was conducted on a number of 24 sexually mature male rabbits of common breed, divided into two numerically equal groups. The subjects from the experimental group were given 20 mg/kg nandrolone decanoate, intramuscularly, twice a week for four consecutive weeks. The control group did not receive any treatment. At the end of the experiment the testes were harvested through bilateral orchiectomy and processed for carrying out histopathological investigations. Testicular fragments were fixated in Stieve’s mixture for 24 hours, dehydrated with alcohol, clarified with butyl alcohol and included in paraffin. Serial sections of 5 μ thickness were stained by Masson's trichrome method modified by Goldner. The testes taken from the control animals showed no detectable changes in optical microscopy. In the case of the animals belonging to experimental lots, there were alterations revealed evidenced by vacuolar dystrophy in the spermatocytes and spermatids, apoptosis, the edema of sperm head, spermatids syncytialization and cell necrosis followed by the disintegration of the seminal cell line with the formation of cellular debris in the seminiferous tubules lumen. These changes have affected part of the seminal cell line from the adluminal compartment (primary and secondary spermatocytes, spermatids and spermatozoids), but not those from the basal compartment (type A1 and B spermatogonia), which proved to be resistant in the conditions of 30 days exposure, at a dose of 20 mg/kg. In this context spermatogenesis is affected only for the period of drug action, but the risk of nandrolone decanoate transmission to humans through animal origin food consumption remains, with negative consequences on the spermatogenesis.