Gestational trophoblastic disease (GTD) comprises hydatidiform mole, invasive mole, epithelioid trophoblastic tumor, placental site trophoblastic tumor, and choriocarcinoma. Ectopic molar gestation (EMG) is exceedingly rare with similar malignant potential like that of an intrauterine molar pregnancy. We report an uncommon case of EMG diagnosed by ultrasonography (USG) with a brief literature review. A 36-year-multipara presented at 8-weeks gestational age with severe abdominal pain and spotting. She underwent a spontaneous abortion 4 months back. Current transabdominal USG revealed a large right adnexal hydatidiform mole with moderate hemoperitoneum. Right ovary could not be discerned separately. Emergency laparotomy with hysterectomy and right adnexal clearance was done. Histopathology showed complete ectopic hydatidiform mole. USG remains the modality of choice for initial assessment of suspected GTD and it allows reliable evaluation of residual or recurrent disease. This report emphasizes the role of USG in the diagnosis of EMG and also, the importance of including EMG in the differential diagnosis of suspected ectopic pregnancy.