A significant number of patients with chronic hepatitis C infection have minimal fibrosis at presentation. Although the short-term outlook for such patients is good, there are limited data available on long-term progression. We assessed the risk of fibrosis progression in 282 patients with chronic hepatitis C with Ishak stage 0 or 1 fibrosis on initial liver biopsy. Progression of fibrosis stage occurred in 118 patients (42%) over a median interval of 52.5 months. Thirteen (5%) progressed to severe (Ishak stage 4 or more) fibrosis. Progression was significantly associated with both age at initial biopsy [odds ratio (OR) for progression of 1.31 per 10 year increase in age] and median alanine transaminase (ALT) levels during follow-up (OR of 1.06 per 10 IU/L increase). There was no significant association with gender, histological inflammatory grade, hepatic steatosis or body mass index. We conclude that hepatitis C with initially mild fibrosis does progress in a substantial proportion of patients and should not be viewed as a benign disease. Early antiviral therapy should be considered in older patients and those with high ALT levels.