Hydatidosis, is a parasitic infestation caused by Echinococcus granulosus. Although the disease most commonly affects liver and lungs, almost all organ and tissue involvements are documented. Rupture into pericardial space which may lead to pericardial effusion, pericarditis and pericardial tamponade, can be seen especially in the patients with cardiac hydatidosis. But rupture of a hepatic hydatid cyst into the pericardial space through a transdiaphragmatic fistula is very rare. In this report, we present imaging findings of a type III hepatic hydatid cyst lesion which ruptured spontaneously into pericardial space and caused pericardial effusion.