Hydatid cysts, which are endemic to certain areas, typically are found in the liver. Spontaneous intraperitoneal rupture, which can be life threatening, is rare. This article presents a case of spontaneous rupture of a hydatid cyst in a 69-year-old woman who was admitted to the emergency department. The patient had no history of trauma. Abdominal ultrasonography and computed tomography suggested rupture of a hydatid cyst. The patient underwent a partial cystectomy, and the cystic area was washed with hypertonic saline and the peritoneal cavity was washed with isotonic saline and drained. Postoperatively, the patient was treated with albendazole for 3 months. No additional pathology was observed at the 3-, 6-, and 9-month follow-ups. Although rare, a ruptured hydatid cyst should be considered in the differential diagnosis of the acute abdomen in a patient residing in an endemic area.