Hydatid disease is relatively frequent in our country and non-invasive ultrasonic imaging techniques have made possible an earlier diagnosis prior to serious complications. Human hydatid disease usually occurs by infestation with Echinococcus granulosus and less frequently with Echinococcus multiocullaris. A twelve-year old girl fell from the swing 12 days ago. Acute abdomen was suspected, and she was operated under emergency conditions. Exploration of the abdomen soon revealed a giant cystic lesion formation, and this development did not fit the development of hydatid cyst pathophysiology.