The present study was conducted on 36 Newzea - land white rabbits assigned into three age groups of two, three, and four months, 12 rabbits for each group of the same age, there were  6 males and 6 females. For each sex, four rabbits were given orally a single dose of L-tyrosine, 100 mg/kg body weight and the other two rabbits, were left as control. The treated groups revealed an increase in the amount, size and the secretory activity of somato- trophs, lactotrophs and LH gonadotrophs, in addition to a marked increase in the amount, size and the secretory activity of thyrotrophs, adrenocorticotrophs and FSH gonadotrophs during the second month of age. From the present results it could be concluded that tyrosine acts as a growth-promoting factor and hormonal inducing factor, it can be used in rabbits for enhancing the puberty of both males and females. It could be recommended that tyrosine can be used on a large scale for regulating the reproductive cycle of males and females in large animals.