Abstract: Background: Tribuls terrestris increases levels of various hormones in steroid family including testosterone, DEHA, and estrogen and for this reason improves sport performance, fertility in men and women, sexual function in men and women. There is, at present, lack of scientific confirmation of these supposed benefits. Therefore, this study aims to investigate the possible effect(s) of Tribuls terrestris on the mouse ovarian morphology and function, alone and in combination with other ovulation modulator agent (clomiphene citrate). Materials & Methods: A total of 49 sexually mature healthy Norway albino female mice were used in this study; 25 for pilot study and 24 for the experimental study. Experimental animals were divided into 4 groups, each contained 6 animals. The 1st group was given Tribuls terrestris, the 2nd group was given clomiphene citrate, the 3rd group was given the two agents together, and the 4th group was control. Treatment was given daily for 10 days via orogastric intubation. Histological, histochemical, cytological and morphometrical studies were carried out. Results: demonstrated that Tribuls terrestris alone causes an increase in the number and size of the mature follicles, with no significant change in the total follicular number, with obvious progesterone and some estrogen effects on the otherwise normal vaginal smears. On the other hand, clomiphene alone revealed no mature follicles and no corpora lutea, with strong estrogen-like effect and minimal progesterone effects on the vaginal smears. When Tribuls terrestris and clomiphene were given together, mature follicles and corpora lutea appeared in relatively large numbers, with estrogen and progesterone effects on the vaginal cytology. Conclusion: Tribuls terrestris can stimulate ovulation when given alone, and oppose the anti-ovulatory effect of clomiphene and resume ovulation when given in combination with it. Keywords: Tribuls Terrestris (Quttub), Clomiphene Citrate, Mice Female Ovaries