Placenta percreta is a rare complication of pregnancy. Rupture of the uterus due to placenta percreta is one of the most urgent obstetrical catastrophes. Recently, we observed a patient who developed placenta percreta accompanied by spontaneous uterine rupture at 28 weeks of gestation. A 29-year old gravida 3, para 1, who had a history of one cesarean section and one miscarriage with dilatation and curetage, was seen at 28 weeks of gestation. An acute abdomen and shock were diagnosed. Immediate laparotomy revealed a transverse rupture on the fundus of the uterus. A hysterectomy was performed. Pathological examination of the uterus showed placenta percreta. Rupture of the uterus due to placenta percreta before the onset of labor is extremely rare.