Background: Lithium is one of the elements of the alkali metal family used in pharmaceutical formulations, which can be used for the treatment of mental disorders, hypothyroidism and depression. This study aimed to determine the chronic effects of lithium on the estrogen, progesterone, FSH, LH hormones and ovarian follicles in adult female Wistar rats.

Materials and Methods: In this experimental study, 40 adult female rats were divided into five groups of 8 rats, including control, sham and three experimental groups receiving intraperitoneal doses of 60, 120 and 180 mg/kg lithium carbonate for 21 days, respectively. At the end of the third week, and after taking the blood samples to measure estrogen, progesterone, FSH and LH hormones, the rats' ovaries were removed and after the preparation and staining of the tissue sections, the follicles were counted.

Results: The results showed that lithium significantly caused to increase the number of atresia follicles and also decrease primordial, primary, and secondary follicles, graphs, corpus luteum and estrogen, progesterone, FSH and LH hormones (P≤0.05).

Conclusion: According to the results of the current study, the use of lithium can increase atresia follicles and decrease other follicles and corpus luteum in adult female rats, and probably due to the reduction of follicles and corpus luteum, the sexual hormone levels are also decreased.