Placenta percreta is the most severe form of morbid adherent placenta in which chorionic villi completely penetrate the uterus upto serosal surface with possibility of rupture in the peritoneal cavity. One of the most dramatic cases of haemoperitoneum concerned a young woman in her 20 weeks of pregnancy, so ill that differential diagnosis ranged from abruptio placentae to most other conceivable intraabdominal surgical catastrophs. A diagnosis of acute haemoperitoneum was established by needle aspiration. At laparotomy the placenta percreta was found perforating the uterine wall.