ABSTRACT Background & aim: Reproductive disorders is one of the major issues in diabetic people and various chemical and herbal medicines has been used for its treatment. Due to the antioxidant and hypoglycemic properties of Avicennia marina, the aim of this study was to determine the effects of mangrove leaves aqueous extract on serum levels of hormones of pituitary- gonadal axis and ovarian follicle numbers in diabetic rats.   Methods: In the present experimental study, 32 female Wistar rats were allocated into equal groups of control, non-treated diabetic and two diabetic groups treated with mangrove leaves aqueous extract at concentrations of 100 and 200 mg/kg.  The diabetes in non-treated diabetic and treated diabetic groups with mangrove extract was induced using an intraperitoneal injection of 120 mg/kg alloxan. Aqueous extract of mangrove leaves were injected to treated diabetic groups, very other day for one month. Saline solution was injected to the animals of control and non-treated diabetic groups. At the end of exprement, serum levels of LH, FSH, estrogen, progesterone and prolactin were measured by ELISA. 5 µm sections of ovarian tissue were prepared and stained with Hematoxylin and Eosin. Then, ovarian follicle numbers were examined by light microscope. Data was analyzed using one-way ANOVA and Post Hoc Tukey statistical tests.   Results: Compared to control group, serum levels of LH, FSH, estrogen, progesterone and prolactin significantly decreased in non-treated diabetic group (p<0.05). Also, number of corpus luteum, primordial, primary, secondary and graph follicle significantly decreased and number of atresia follicle significantly increased compared to the control group (p<0.05). Compared to non-treated diabetic group, administration of mangrove leaves aqueous extract with concentrations of 100 and 200 mg/kg significantly increased serum levels of LH, FSH, estrogen, progesterone and prolactin (p<0.05). Also, number of corpus luteum, primordial, primary, secondary and graph follicle significantly increased and number of atresia follicle significantly decreased compared to non-treated diabetic group (p<0.05).   Conclusions: The results indicate significant effect of mangrove leaves extract on increases serum levels of gonadotropins, estrogen, progesterone and prolactin in diabetic rats. Also it has protective effect on ovarian tissue. Therefore, consumption of Avicennia marina could be effective in improving hormonal disorders and ovarian tissue damage in patients with diabetes.