Background: Thyroid hormones are key regulators for a variety of biological processes including reproduction. The alterations in thyroid hormones levels were found to disturb the proper functioning of the ovary impairing fertility. Objective: To investigate the effect of Carbimazole induced hypothyroidism on the ovaries of adult female albino rats. Materials and methods: Forty five adult female albino rats were used and were classified into three equal groups: Group I (Control group):received 0.5 ml of distilled water every day orally by gastric tube for three months , Group II (Hypothyroid group) received Carbimazole at a dose of 5mg dissolved in distilled water every day orally by gastric tube for three months to induce hypothyroidism, and Group III (Recovery Group) ceased to receive Carbimazole for three months to examine the changes after the stoppage of the treatment.      The changes were tested by measuring the serum levels of TSH, T4 and T3, FSH, LH, E2 and PRL. Moreover, the effects on the structure of the ovary were investigated via histological studies by using Hematoxylin and Eosin, and Masson's Trichrome along with immuno-histochemical studies using Vimentin and α- smooth muscle actin. Results: The examination of ovarian specimens revealed a change in the normal architecture of the ovary, where the ovarian cortex showed an apparent decrease in the number of growing follicles with large fluid-filled cystic follicles and multiple atretic follicles. Marked condensation of the interstitial cells among the follicular component of the cortex was identified with engorged blood vessels which were reversed upon stoppage of the intake of the drug. Conclusion: The use of Carbimazole in induction of hypothyroidism affected the normal functioning of the ovary via acting on different levels.