Interferon treatment for chronic hepatitis C reduces the incidence of hepatocellular carcinoma (HCC) in sustained responders. However, estimation of the effect of interferon treatment on HCC development in nonresponders is yet to be fully implemented. We conducted a meta-analysis of 3 randomized controlled trials and 6 prospective cohort studies, including 3,246 patients (1,922 patients received interferon treatment) to estimate the effect of single-course interferon treatment on HCC development in patients with chronic hepatitis C. Single-course interferon treatment prevented HCC development (RR 0.45; 95% CI 0.31-0.65). This preventive effect was shown even in nonresponders (RR 0.48; 95% CI 0.25-0.90). By subgroup analyses, single-course interferon treatment reduced HCC incidence in cirrhotic patients (RR 0.49; 95% CI 0.29-0.84), patients with annual HCC incidence less than 3% in control group (RR 0.42; 95% CI 0.26-0.66) and patients with annual HCC incidence of 3% or more in control group (RR 0.46; 95% CI 0.26-0.83). Furthermore, HCC incidence was reduced in 3 studies with follow-up period less than 5 years (RR 0.38; 95% CI 0.21-0.66) and in 6 studies with follow-up period of 5 years or more (RR 0.46; 95% CI 0.28-0.76). In conclusion, single-course interferon treatment was shown to prevent HCC development in chronic hepatitis C, even in nonresponders. This preventive effect may be speculated to be due to anti-inflammatory effect on persistent necro-inflammation and blocking progression of fibrosis in liver. Even if sustained virological response is not achieved, interferon may be worth administering in order to reduce HCC incidence in patients with chronic hepatitis C.