INTRODUCTION: The impacts of viral load, genotype, age, sex and BMI on the clinical course of acute hepatitis C are poorly defined. Here we studied 259 patients with acute HCV infection recruited in the German Hep-Net data base between 1998 and 2008. Antiviral treatment with interferon alpha was initiated in 171 patients (66 %) within 4 months after the diagnosis of acute hepatitis C. RESULTS: In this cohort (i) the mode of infection was associated with age as iv-drug users were significantly younger than non-iv-drug users while the proportion of patients who acquired HCV by medical procedures increased with age; (ii) patients younger than 30 years were more often infected with genotype 3 (26 % versus 8 % for patients older than 50 years; p = 0.03); (iii) 51 % of patients were icteric and 28 % presented with a 30-fold elevation of liver enzymes, however, no fulminant hepatic failure occurred; (iv) HCV genotype was not associated with disease severity and time to onset of symptoms; (v) low HCV viremia was associated with lower serum AST levels and a longer time from exposure to onset of symptoms; (vi) disease severity was independent from the mode of infection, age, sex and body mass index (BMI). CONCLUSIONS: In this large cohort of patients admitted for antiviral therapy, acute hepatitis C took a rather mild course of disease in the majority of patients. Disease severity was not associated with HCV genotype, viral load, age, sex and BMI.