Introduction: Heterotopic pregnancy is the existence of both intrauterine pregnancy and ectopic pregnancy simultaneously. Heterotopic pregnancy (HP) has been a rare type of multifetal pregnancy. Heterotopic abdominal pregnancy (HAP) is a very rare diagnosis with very few reported cases. Case Presentation: We reported a rare case of HAP in a 32-year-old woman (G2L1) with a history of 13 weak amenorrhea and mild pelvic pain presenting with two live fetuses in the 13th week. The patient also did not mention any risk factor of ectopic pregnancy such as pelvic inflammatory disease, assisted reproductive techniques, endometriosis, and multiparity. Diagnosis of HAP was performed with the use of sonography and magnetic resonance imaging. We managed the patient with emergency laparotomy due to acute abdominal pain a few hours after admission. Laparotomy revealed the rupture of the left fimbria with 500 cc hemoperitoneum. The excision of the ectopic gestational sac in the cul-de-sac and left salpingectomy with preserving the intrauterine fetus was performed. The patient finally gave birth to one live term birth. Conclusions: Physicians should consider the possibility of HP in women with spontaneous pregnancy and abdominal pain. Both sonography and MRI should be performed to help timely diagnosis.