The effect of an isolated fraction, with bradykinin potentiating activity, from the venom of the Egyptian Scorpion, Buthus Occitanus, on the body weight, overies, uteri, oestradiol and progestexone levels, was studied in immature (3 weeks-old) female guinea pigs. Intraperitoneal injection of a single dose (1 ug/g B.W. ) of the venom fraction produced a non-significant increase in the body weight of treated than control animals. However, the ovaries of treated guinea pigs showed different stages of follicular activity including Graafian follicles, together with an increase in the thickness of their endometrium and number and diameter of endometrial glands against primary and growing ovarian follicles, thin endometrium and few narrow-lumen endometrial glands in control animals. On the other hand, 5 successive injections of the venom fraction produced a significant (P < 0.001) increase in the body weight of treated animals. Mature follicles and corpora lutea were observed in their ovaries together with marked endometrial activity in their uteri. This was accompanied with a significant elevation of oestradiol Level (P<0.001) and progesterone level (P < 0.05) in the sera of treated than control guinea pigs.