Hydatidosis; is a zoonotic disease caused by Echinococcus granulosus and characterized by infiltration of inflammatory cells. This study was investigated the hematological and histopathological changes in the hearts of rats injected with protoscoleces. Rats were injected with protoscoleces collected from either liver of sheep, goats, and cows (from the abattoir of Al-Muthanna province, south of Iraq) or isolated from infected humans from Al-Hussein Teaching Hospital. Sheep protoscoleces showed a significant increase of lymphocytes that refer to the induction of a high response of the immune system in rats. The numbers of WBC, RBCs, and platelets were generally increased in rats injected with protoscoleces isolated from sheep and goats. These changes could refer to the activation of defense mechanisms against the hydatid injected materials. However, the levels of MCV, MCH, MCHC, MPV and PDW were less than normal values. Heart sections of rats injected with protoscoleces isolated from humans showed clear histological changes. While TSP, TGP and TCP exhibited variant histopathological changes such as infiltration of inflammatory cells, pink glass appearance and congestion of arteries. Thus, these alterations can be considered as additional evidence of how the immune response reacts against the injected materials in the heart.