Active immunization against hormones is consid- red one of the best methods to investigate their effects. Six Barki rams were immunized against LH hormone (hCG, Pregnyl- Organon) which was emulsified with complete Fruend's adjuvant. Reproductive function of rams, testicular measurements, Semen parameters and testosterone level, were estimated before and for eight weeks after immunization. The results revealed that there is no significant effect on semen volume, minor and major sperm abnormalities. On the other hand, Duncan's Multiple Range test revealed differences in mass motility individual motility, sperm concentration and live dead ratio. It was found that there was a gradual decrease in sperm concentration, live /sperm percent after immunization while total testicular circumference decreasedgradually from the 1^st to 5^th week after immunization and then returned back to the normal circumferences during the 8^th week after immunization.