Hepatic hydatid cysts may cause serious complications. Intraperitoneal rupture of hepatic hydatid cyst is rarely seen and the prognosis can be fatal. By experience, we know that it might be difficult to diagnose an unruptured cyst expulsed into the peritoneal cavity. In this report, we present the case of a 54-year-old man with an intraperitoneal cystic mass of 10 cm of diameter which had extruded out from the liver due to a blunt abdominal trauma.