Background: The key end point for treatment efficacy in chronic hepatitis C is absence of detectable virus at six months after treatment. However, the inciden ce of clinical events during long term followup of patients with sustained virol ogical response is still poorly documented and may differ between the Eastern an d Western world. Aims: To assess clinical end points during long term followup o f European patientswith a sustained virological response to interferon monothera py. Methods: Meta-analysis of individual patient data from eight European proto colled follow up studies of interferon treatment for chronic hepatitis C. Result s: A total of 286 sustained virological responders and 50 biochemical responders (detectable virus but normal alanine aminotransferase levels) were followed up for 59 months. Fifteen sustained virological responders (5.2%) had cirrhosis be fore treatment and 112 (39%) had genotype 1. The late virological relapse rate after five years of follow up was 4.7%(95%confidence interval (CI) 2.0-7.4) a mong sustained virological responders; all late relapses occurred within four ye ars after treatment. Among sustained virological responders, the rate of decompe nsation after five years of followup was 1.0%(95%CI 0.0-2.3) and none develop ed hepatocellular carcinoma (HCC). Survival was comparable with the general popu lation, matched for age and sex, the standard mortality ratio being 1.4 (95%CI 0.3-2.5). Clinical outcome of patients with cirrhosis was similar to other sustained virological responders. For bioc hemical responders, the rates of development of decompensation and HCC during lo ng term follow up were 9.1%(95%CI 0.5-17.7) and 7.1%(95%CI 0-15.0), respec tively. Conclusions: Five year survival of European sustained virological respon ders was similar to the overall population, matched for age and sex. No HCCs wer e detected during long term follow up. Background: The key end point for treatment efficacy in chronic hepatitis C is not detectable virus at six months after treatment. However, the inciden ce of clinical events during long term follow up of patients with sustained virol ogical response is still poorly documented and may differ Between the Eastern an d Western world. Aims: To assess clinical end points during long term follow up of European patients with a sustained virological response to interferon monothera py. Methods: Meta-analysis of individual patient data from eight European proto colled follow up studies of interferon Treatment for chronic hepatitis C. Fifteen sustained virological responders and 50 biochemical responders (detectable virus but normal alanine aminotransferase levels) were followed up for 59 months. Fifteen sustained virological responders (5.2%) had cirrhosis be fore treatment and 112 (39%) had genotype 1. The late virological relapse rate after five years of follow up was was 4.7 % (95% confidence interval (CI) 2.0-7.4) a mong sustained virological responders; all delayed relapses occurred within four ye ars after treatment. Among sustained toxicological responders, the rate of decompensation was five years after follow up was 1.0% (95 % CI 0.0-2.3) and none develop ed hepatocellular carcinoma (HCC). Survival was comparable with the general popu lation, matched for age and sex, the standard mortality ratio being 1.4 (95% CI 0.3-2.5). Clinical outcome of patients For bioc hemical responders, the rates of development of decompensation and HCC during lo ng term follow up were 9.1% (95% CI 0.5-17.7) and 7.1% (95% CI 0-15.0 ), respec tively. Conclusions: Five year survival of European sustained virological responders ders was similar to the overall population, matched for age and sex. No HCCs wer e detected during long term follow up.