Scorpion envenomation is one of the important issues in human and animal health especially in tropical regions. Mesobuthus eupeus is one of the 6 dangerous scorpions in Khouzestan province, Iran. In this research, changes of hemogram and erythrocyte osmotic fragility due to scorpion envenomation and the protective effect of polyvalent antivenom and quercetin in rat were studied. Ninety male wistar rats were randomly divided into 5 groups. in Group 1 (control group) normal saline (0.5 ml), group 2  scorpion venom (1.5 mg/kg), group 3 scorpion venom (1.5 mg/kg) and 20 min later antivenom (2.5 ml/kg), group 4 scorpion venom (1.5 mg/kg) and 20 min later quercetin (200 mg/kg), group 5 scorpion venom (1.5 mg/kg) and 20 min later antivenom (2.5 ml/kg) and quercetin (200 mg/kg) was administered intraperitoneally. Blood samples were collected, intracardially in 1, 3 and 24 hours post envenomation, with 6 rats in each sampling. Hemogram results showed an insignificant decrease in PCV and Hb, in groups 2 and 4, 24 hours post envenomation which was not observed in groups 3 and 5. In all evenomed groups (2, 3, 4 and 5), there was also a significant increase in platelet count, one hour after injection, and a significant increase in neutrophils and decrease in lymphocytes, 3 hour post envenomation. Additionally, an increase in osmotic fragility was seen in all venom treated groups that was significant in salt dilutions of 0.45, 0.40 and 0.35, percent compared to control group (p<0.05). It can be concluded that Mesobuthus eupeus venom can increase erythrocyte osmotic fragility and induce neutrophilia. In addition, although separate or concurrent administration of antivenom or quercetin improve erythrocyte indices, but they do not make any protective effects on erythrocyte osmotic fragility and leukogram post scorpion envenomation, in dose and timings applied in this study.