In this study, fourty-fiVe merino lambs were used. These animals were divided into there groups. Twelve mg of Zeranol were implanted sulbcutaneously to ear of the first and second groups lambs. Fourty days later, the same dose of Zeranol was reimplanted to the second, group lamlbs. The remaining 15 lambs were served as nonimplanted controls. Five lambs belonging to each group were slaughtered at 80, 1/20 and 160 days after implantation. Before slaughtering the lambs body weight were measured. Then testes, epididymides, vesicular glands and bulbourethral glands were weighted.

The testes weights and their ratio to the body weights in the Zeranol implanted groups slaughtered at the 80 th days were significantly lower than the control group.

No differences Were found in testicular of lambs slaughtered at the 120 th and 160 th days. On the other hand, any significant differences were not observed in the bulbourethral glands, vesicular glands and epi-didymal weights between the three groups.