Although the anti-hepatitis C virus (HCV) effect of statins in vitro and clinical efficacy of fluvastatin combined with Pegylated interferon (PEG-IFN)/ribavirin therapy for chronic hepatitis C (CHC) have been reported, the details of clinical presentation are largely unknown. We focused on viral relapse that influences treatment outcome, and performed a post-hoc analysis by using data from a randomized controlled trial. Thirty-four patients in the fluvastatin group and 33 patients in the non-fluvastatin group who achieved virological response (complete early virological response [cEVR] or late virological response [LVR]) with PEG-IFN/ribavirin therapy were subjected to this analysis. Factors contributing to viral relapse were identified by using multiple logistic regression analysis. Relapse rate in patients with cEVR was significantly lower in the fluvastatin group (2 of 23, 8.7%) than in the non-fluvastatin group (9 of 26, 34.6%; P = 0.042). The use of fluvastatin decreased relapse rate in patients with LVR (27.3% vs 57.1%), though not significantly. Overall, relapse rate was significantly lower in the fluvastatin group (14.7%; 5 of 34) than in the non-fluvastatin group (39.4%; 13 of 33; P = 0.027). Multivariate analysis identified absence of fluvastatin (P = 0.027, odds ratio [OR] = 3.98, 95% confidence interval [CI] = 1.05-15.11) and low total ribavirin dose (P = 0.002, OR = 2.41, 95% CI = 1.38-4.19) as independent factors contributing to relapse. The concomitant addition of fluvastatin significantly suppressed viral relapse, resulting in the improvement of sustained virological response rate, in PEG-IFN/ribavirin therapy for CHC patients with HCV genotype 1b and high viral load.