Patients with chronic hepatitis C can have variable clinical progression. Hepatic histological alterations appear to be milder in asymptomatic subjects who have persistently normal ALT levels. Aims: To evaluate the severity of histological liver alterations in blood donors with normal and elevated ALT levels. Methods: We evaluated volunteer blood donors from the main blood bank of the city of Salvador-Brazil. Those who were anti-HCV positive were invited to participate in the study. Serum ALT and AST levels were measured at two time points, two months apart. Donors were divided into two groups: group I, individuals with ALT ≥ 1.5 times the upper limit of normal in at least one time point and group II, individuals with normal or near normal ALT, at both time points. Results: We evaluated 30,232 blood donors and 528 (1.7%) of them were anti-HCV positive. Eighty-two attended our service and HCV infection was confirmed in 66 individuals. Male gender predominated in both groups; the mean age was 36 for group I, and 33 for group II. Tattoos and intravenous illicit drug use were frequently-encountered risk factors. Liver biopsy was done in 43 subjects. Among donors with elevated ALT, two (10%) had minimum alterations, while in group II normal liver or minimum alterations were observed in six (26%) subjects. Chronic hepatitis or cirrhosis was encountered in 35 (81%) individuals: three (15%) and five (21%) subjects had chronic hepatitis without inflammatory activity, 10 (50%) and 11 (48%) had minimum to moderate activity and five (25%) and one (4.3%) had cirrhosis, in groups I and II, respectively (P was not significant). Conclusions: The prevalence of anti-HCV among this population of volunteer blood donors was 1.7%, and these subjects had few liver histological alterations or chronic hepatitis and cirrhosis. Liver injury severity was significant in patients with elevated ALT, however subjects with normal levels may also present chronic hepatitis and cirrhosis.