Background: Aggressive behaviors in human and experimental animals have previously been described following induced pain. Aggression in rodents has been attributed to genetic and environmental factors, such as pain. A major complication of scorpion envenomation is severe pain in animals and humans. Considering that envenomation by black scorpion (Androctonus crassicauda) induces severe pain, the present study was conducted to investigate the effects of the venom on inducing aggressive behaviors in rats due to the pain from stinging. Methods: Rats in the control (n=20) and experimental groups (n=20) were injected with 0.5ml physiological serum or 1µg/ml of black scorpion venom dissolved in 0.5ml physiological serum, respectively, in the dorsal vein near the tail. Changes in behaviors were monitored photographically among the rats in both groups. Results: Following the injection of the scorpion venom, considerable agitation and fights occurred among the experimental rats, presumably due to the severe pain induced by the venom. However, there was no such abnormal behavior observed in the control rats and in the experimental rats before the venom injection. Conclusion: The induced pain post envenomation in rats caused violent changes in their behaviors, which were highly likely associated with the venom injection.