Background The aim of this research was to investigate the impact of post-transplantation adjuvant chemotherapy in the prevention of tumor recurrence and metastasis for hepatocellular carcinoma (HCC) exceeding Milan criteria after liver transplantation.Methods A total of 117 patients with HCC exceeding the Milan criteria who had undergone orthotopic liver transplantation (OLT) from August 2002 to February 2009 were enrolled and retrospectively analyzed.The patients were divided into four groups according to chemotherapy regimens and the impact of different chemotherapy regimens on survival,disease-free survival,and adverse effects were compared.Results One year survival rates for the gemicitabine,conventional chemotherapy,oxaliplatin plus capecitabine and the best supportive care (BSC) group were 87.5％,84.2％,81.6％,and 67.5％.The 3-year survival rates were 48.1％,25.9％,31.6％,and 33.7％,respectively for the four groups.One year disease free survival rates for the four groups were 69.8％,47.4％,53.8％,and 45.7％ respectively.And 3-year disease free survival rates were 43.2％,23.7％,23.6％,and 25.1％ for the four groups.Stratification analysis showed that the gemcitabine regimen and conventional chemotherapy could significantly improve the survival rate and disease free survival rate for HCC patients who had major vascular invasion and/or microvascular invasion after liver transplantation compared with BSC group.Conclusions For HCC patients beyond Milan criteria,especially who had vascular invasion and/or micorvascular invasion,post-transplantation adjuvant chemotherapy can significantly improve survival.Gemcitabine is a proper regimen for postoperative adjuvant chemotherapy.Conventional chemotherapy can also benefit patients,but the adverse effects are not satisfactory.