To retrospectively evaluate risk factors for aggravation of esophageal varices (EV) within 1 year after balloon-occluded retrograde transvenous obliteration (B-RTO) of gastric varices (GV) and to clarify suitable timing for upper endoscopy to detect EV aggravation after B-RTO.Participants included 67 patients who underwent B-RTO for GV between January 2006 and December 2010. Whether EV aggravation occurred within 1 year was evaluated, and the time interval from B-RTO to aggravation was calculated. Factors potentially associated with EV aggravation were analyzed.B-RTO was successfully performed in all patients. EV aggravation at 1 year after B-RTO was found in 38 patients (56.7 %). Multivariate logistic regression analysis showed that total bilirubin (T-bil) (P = 0.032) and hepatic venous pressure gradient (HVPG) (P = 0.011) were significant independent risk factors for EV aggravation after B-RTO. Cutoff values of T-bil and HVPG yielding maximal combined sensitivity and specificity for EV aggravation were 1.6 mg/dL and 13 mmHg, respectively. The patients with T-bil ≥ 1.6 mg/dL or HVPG ≥ 13 mmHg had a median aggravation time of 5.1 months. All five patients with ruptured EV belonged to this group. In contrast, patients with T-bil < 1.6 mg/dL and HVPG < 13 mmHg had a median aggravation time of 21 months.T-bil and HVPG were significant independent risk factors for EV aggravation after B-RTO. The patients with T-bil ≥ 1.6 mg/dL or HVPG ≥ 13 mmHg require careful follow-up evaluation, including endoscopy.