The type, incidence, and severity of complications of balloon-occluded retrograde transvenous obliteration (B-RTO) for gastric varices should be precisely estimated. Complications were evaluated in 38 patients who had fundic gastric varices and 43 B-RTO procedures during injection of ethanolamine oleate (phase 1), within 4 h after injection (phase 2), 24 h after injection (phase 3), and from 24 h to 10 days after injection (phase 4). Endoscopic evaluation at 8 weeks showed resolution of gastric varices in 35 of 38 patients (92%) and smaller varices in the remaining three (8%). B-RTO caused transient hypertension in 35% of patients, hemoglobinuria in 49%, and fever in 33% during phases 1, 2, and 3, respectively. Pleural effusion, pulmonary infarction, ascites, gastric ulcers with unique appearance, localized mosaic-like change of gastric mucosa, and hemorrhagic portal hypertensive gastropathy were noted in phase 4. There were no fatalities. Lactate dehydrogenase, aspartate aminotransferase, and bilirubin increased on day 1. Each datum was retrieved within 7 days. The severity of lactate dehydrogenase elevation correlated significantly with the volume of infused ethanolamine oleate. Thus, B-RTO is a safe and effective management of fundic varices. However, short-term hemodynamic change after B-RTO may cause gastric mucosal damage. Pulmonary infarction and pleural effusion are potential complications.