['To evaluate the possible relationship between aminotransferases levels and markers of oxidative stress in chronic hepatitis C patients.', 'Patients without treatment for hepatitis were divided in to group I (15-39 U/L); group II (41-76 U/L) and group III (81-311 U/L) of activity alanine aminotransferase (ALT). Blood markers of oxidative stress [catalase (CAT), glutathione peroxidase (GPx), thiobarbituric acid-reactive species (TBARS), nonprotein and protein thiol (NP-SH and P-SH) groups and vitamin C] were determined.', 'P-SH and NP-SH levels, TBARS, GPx and CAT were not different between groups. Vitamin C was significantly decreased in groups II (P=0.03) and III (P=0.001) when compared with group I and correlated negatively with aspartate aminotransferase (AST; r=-0.29, P=0.042).'] Is plasmatic vitamin C in nontreated hepatitis C patients negatively associated with aspartate aminotransferase?