BACKGROUND: Uterine rupture secondary to placenta percreta has been observed in multiparous patients. These cases are typically associated with a prior history of uterine trauma or infection: hysterotomy, myomectomy, control resection, dilatation and curettage, manual removal of the placenta or endometritis. Spontaneous rupture of the primigravid uterus without a history of trauma or infection is an exceedingly rare occurrence. This case represents the second reported in the medical literature and the first to result in a live-born infant. CASE: A 23-year-old, African American primigravida at 26 weeks' gestation presented with acute-onset abdominal pain, severe hypotension, tachycardia and fetal heart rate decelerations. Blood product replacement teas initiated, and an emergency laparotomy was performed for a presumptive diagnosis of intraabdominal hemorrhage. A significant hemoperitoneum was encountered, with the fetus floating freely in the peritoneal cavity. The uterus had a fundal rupture with a clinically apparent placenta percreta that necessitated performing a total abdominal hysterectomy. The patient recovered uneventfully, and the infant survived without significant morbidity. CONCLUSION: Spontaneous rupture of the primigravid uterus can occur in the absence of a history of uterine trauma or infection. Ifa gravid woman presents with hypotension, abdominal pain and fetal distress, the differential diagnosis should include rupture of the uterus, regardless of purity or gynecologic history. Rapid diagnosis, blood product replacement and emergency laparotomy are the key steps in successful management.