The pharmacological properties of Vespa orientalis venom and its toxicity against the mammalian albino rat, Rattus albus was studied by direct stinging or by using the venom sac homogenate. The degree of hemolysis and other hematological changes as induced by stinging or injection the rat, Rattus albus with venom sac homogenate (VSH) were investigated in-vivo. The results obtained showed that both stings and venom injection had toxic effects on the blood of rats, especially the multiple stings (3 or 4 stings) and high doses of VSH (6 and 12mg/1ml saline solution). These treatments evoked a significant decreased in WBCs, RBCs, HG and HCTs but a significant increase of PLTs indicating that Vespa orientalis venom has a hemolytic activity on the in-vivo rat blood.