Spontaneous hemoperitoneum is defined as bleeding within the peritoneal cavity of non-traumatic and non-iatrogenic etiology. It is a rare and life-threatening condition during pregnancy. Spontaneous hemoperitoneum is considered idiopathic when the source of bleeding is not detected during the exploratory laparotomy. The authors report two cases of spontaneous hemoperitoneum during pregnancy with sudden onset of abdominal pain during the third trimester of their pregnancy. Cesarean section was performed for fetal distress. In both cases, hemoperitoneum with a large quantity of blood was found, but the source of bleeding could not be identified during surgical exploration.