Type 2 diabetes mellitus (T2-DM) is a chronic metabolic disorder characterized by tissue resistance to insulin action. Leiurus quinquestriatus venom (LQV) contains a variety of bioactive components that can be used for the treatment of various diseases. This study aimed to determine the ameliorative role of LQV on the histopathological changes in splenic tissues of T2-DM rats. Forty male Sprague Dawley rats were divided into 4 groups (n = 10) as follows; Gp1 (Control group) was fed on a normal balanced diet. Gp2 (Diabetic group) was fed on a high-fat diet (HFD) for 12 weeks and then injected with streptozotocin (STZ) (30 mg/kg) i.p. Diabetic Gp3 and Gp4 groups had been injected with metformin (Met) (150 mg/kg) or LQV (1/10 of LD₅₀), respectively. After two months of treatment, the total body weight relative splenic weight changes, and blood glucose. Also, histopathological and immunohistochemical investigations (CD-3 immunoreactive antibody) in splenic tissues were examined. The results showed that induction of T2-DM in rats led to a significant decrease in the total body weight (-38.56%), relative spleen weight (0.23 ± 0.03), and increase in the level of blood glucose (382.56 ± 2.77 mg/dL). In addition, several histopathological and immunohistochemical changes were observed in splenic diabetic tissues. The treatment of T2-DM rats with LQV led to an improvement in the total body weight of rats (4.07%), relative spleen weight (0.40 ± 0.02), decrease in the blood glucose levels (115.47 ± 1.07 mg/dL), ameliorated the histopathological and immunohistochemical changes occurred in splenic tissues of T2-DM rats.