The purpose of this study was to evaluate the efficacy of postoperative adjuvant chemotherapy with FOLFOX regimen on the outcome after LT for HCC patients who did not meet the Milan criteria. Ninety-five consecutive HCC patients with liver cirrhosis undergoing LT were enrolled. Fifty-eight who did not meet the Milan criteria were randomized to open-label treatment with or without adjuvant chemotherapy after LT (n = 29/group). The FOLFOX chemotherapy protocol comprised 3-week cycles of oxaliplatin 100 mg/m2 on day 1, leucovorin (calcium folinate, CF) 200 mg/m2 on day 1 followed by 3-day, and 5-fluorouracil (5-FU) 2000 mg/m2 as a 48-h continuous infusion, for up to six courses in the 1st year after transplantation. Median survival was extended by 4.57 months by combination chemotherapy. The 1- and 3-year survival rates were 89.7% and 79.3% with chemotherapy versus 69.0% and 62.1% without chemotherapy. The cumulative 1-year survival was significantly increased by chemotherapy (log-rank test, P = 0.043). The 6-month tumor-free survival rate was 24.1% higher with chemotherapy than without. The recurrence rate after LT was significantly different between the two groups at 6 months (P = 0.036), but not at 3 years (P = 0.102). The chemotherapy regimen was generally well tolerated. Post-LT adjuvant chemotherapy with oxaliplatin/5-FU/CF could not prevent tumor recurrence post-LT but may contribute to improve the survival of HCC patients who do not meet the Milan criteria. These results should be verified in a larger sample with a longer follow-up period.