BACKGROUND: Mesobuthus eupeus is an indigenous scorpion species in Southwest Iran which is respon- sible for the majority of scorpion sting cases in Khuzestan province. OBJECTIVES: The effects of M. eupeus venom were investigated on the chief metabolic hormones in rats. METHODS: A total of 45 Albino male rats were divided into 3 equal groups: group 1 (control): 0.5 ml normal saline was administered intraperitoneally (IP); group 2 and 3: M. eupeus venom was administered with a dose of 1 and 2 mg/kg IP, respectively. Sampling was performed at 8, 24, and 48 hours after venom/ saline injection. RESULTS: The levels of thyroxine (T4) and triiodothyronine (T3) were significantly lower in both venom receiving groups (groups 2 and 3) than in the control group, dose-dependently, at all sampling times. There was a significant decrease in insulin level in both intoxicated groups compared to the control group at all sampling times. Glucagon, cortisol and subsequently glucose concentrations were significantly increased in both groups receiving the venom (groups 2 and 3) compared to the control group at 8 and 24 hours following envenomation. CONCLUSIONS: The findings of this study indicate that M. eupeus venom can suppress the secretion of essential metabolic hormones including T3, T4, and insulin and stimulate the release of glucagon, and cor- tisol, leading to hyperglycemia.