The study investigated the major phenolic compounds of Aloe vera leaf (AVL) by the high-performance liquid chromatography (HPLC) method, and its protective effect on ovaries under oxidative stress of streptozotocininduced diabetic rats. The study was conducted on control (untreated healthy rats; C), diabetes (untreated diabetic rats; D) and diabetes+A. vera treatment (diabetic rats treated with A. vera; D+A) groups. D+A group was given an ethanolic extract of A. vera (300 mg/kg) for 14 days. Major phenolic compounds of AVL were chlorogenic acid and rutin. alanine transaminase (ALT) and aspartate aminotransferase (AST) levels increased in D group compared to others groups (P<0.01). Alkaline phosphatase (ALP) and albumin levels were lower and higher in the C group than in other groups, respectively (P<0.01). In the D group compared to other groups, oxidative stress index (OSI) and total oxidant status levels increased, while total antioxidant status level decreased in both ovarian tissues and blood (P<0.01). Preantral and antral follicle counts decreased in the D group according to other groups (P<0.01) and atretic follicle count increased (P<0.05). Proliferating cell nuclear antigen (PCNA) expression level (P<0.01), and B-cell lymphoma-2-associated-Xprotein (Bax; P<0.01) and tumor necrosis factor-alpha (TNF-α) expression levels (P<0.05) decreased and increased in group D according to other groups, respectively. In conclusion, treatment with AVL decreased OSI, improved follicular dynamics, and restored Bax, TNF-α and PCNA expression in diabetic rats.