['To investigate alanine aminotransferase (ALT) and sustained virological response (SVR) in chronic hepatitis C (CHC) during peginterferon-ribavirin treatment.', 'One hundred and fifty-one genotype 1 CHC patients underwent treatment for 48 wk with peginterferon and ribavirin, and were retrospectively divided into two groups as having a rapid virological response (RVR) (Group 1, n = 52) and not having an RVR (Group 2, n = 99). We also subdivided each group into two according to the initial ALT level being high (Group 1h and Group 2h) or normal (Group 1n and Group 2n). HCV RNA and ALT levels were measured at baseline; at 4, 12, 24 and 48 wk during the treatment period; and at 24 wk follow-up. ALT levels were also obtained at 8 wk. According to the results of ALT, patients were enrolled in either the follow-up abnormal or follow-up normalized ALT groups at each interval. Patients with high and normal ALT levels were compared for each interval in terms of SVR.', 'The SVR rates were 83% vs 40% (P = 0.000), 82% vs 84% (P = 0.830), and 37% vs 44% (P = 0.466) when comparing Group 1 with 2, 1h with 1n, and 2h with 2n, respectively. In Group 2h, the SVR rates were 34% vs 40% (P = 0.701), 11% vs 52% (P = 0.004), 12% vs 50% (P = 0.007), 7% vs 50% (P = 0.003), 6% vs 53% (P = 0.001), and 0% vs 64% (P = 0.000) when comparing patients with high and normalized ALT levels at week 4, 8, 12, 24, 48 and 72, respectively. The multiple logistic regression analysis revealed that RVR (OR = 7.05; 95%CI: 3.1-16.05, P = 0.000), complete early virological response (cEVR) (OR = 17.55; 95%CI: 6.32-48.76, P = 0.000), normalization of ALT at 8 wk (OR = 3.04; 95%CI: 1.31-7.06, P = 0.008), and at 12 wk (OR = 4.21; 95%CI: 1.65-10.76, P = 0.002) were identified as independent significant predictive factors for SVR.'] Does alanine aminotransferase normalization at week 8 predict viral response during hepatitis C treatment?