BACKGROUND: A combined antiviral and tumoricidal effect of interferon (IFN) is assumed to occur after resection or ablation of hepatocellular carcinoma (HCC). METHODS: An electronic search of the Medline, Embase and Central databases from January 1998 to October 2007 was conducted to identify randomized controlled trials evaluating adjuvant effects of IFN after curative treatment of HCC. A meta-analysis was performed to estimate the effects of IFN on 2-year outcome. RESULTS: Seven trials enrolling a total of 620 patients were included in the meta-analysis. Adjuvant treatment with IFN significantly reduced the 2-year mortality rate after curative treatment of HCC, with a pooled risk ratio of 0.65 (95 per cent confidence interval 0.52 to 0.80); P < 0.001) in absence of any significant heterogeneity (I(2) = 0 per cent, P = 0.823 for chi(2)). The effect on reduction of tumour recurrence was less pronounced but still significant (pooled risk ratio 0.86 (95 per cent c.i. 0.76 to 0.97); P = 0.013). IFN had to be discontinued in 8-20 per cent of patients. CONCLUSION: IFN has a significant beneficial effect after curative treatment of HCC in terms of both survival and tumour recurrence.