BACKGROUND Molar ectopic pregnancies are rare. A literature search revealed that molar ectopic pregnancies are overdiagnosed. METHODS A 25-year-old, G5P3013, African American woman presented to a com- munity hospital with sudden onset of sharp, stabbing, low abdominal pain and nausea and vomiting. Quantitative hCG was 6,644 mIU/mL and ultrasound demonstrated increased vascularity and a hypoechoic, partially tubular collection in the left adnexa concerning for ectopic pregnancy. Laparoscopy revealed a small amount of blood and a slight bulge in the left uterine cornu, which ruptured during blunt exploration. Laparotomy revealed the ruptured left uterine cornu with tissue protruding. A wedge resection of the cornu was performed. The pathologic findings from the cornual resection were consistent with a complete mole. Immunohistochemical staining was performed using p57 analysis 1.5 years later and was consistent with early ectopic pregnancy. CONCLUSIONS p57 analysis is an important adjunct in the accurate diagnosis of ectopic hydatidiform molar pregnancy.