In order to assess the liver protective activity and the antioxidant properties of a new silybin complex (IdB1016), we carried out a short-term pilot study on 20 patients with chronic active hepatitis (CAH), randomly assigned to 240 mg of silybin b.i.d. (10 patients, 4 m/6 f, mean age: 50 years) or placebo (10 patients, 2 m/8 f, mean age: 55 years). Blood samples were collected before and after 7 days of treatment for liver function tests (LFTs), malonaldehyde (MDA) as an index of lipid peroxidation, and copper (Cu) and zinc (Zn), two trace elements involved in protecting cells against free radical-mediated lipid peroxidation. In the treated group, there was a statistically significant reduction of mean (+/- SEM) serum concentrations of aspartate aminotransferase (AST) from 88.0 (+/- 13.3) to 65.9 (+/- 7.5) u/l, (p < 0.01), of alanine aminotransferase (ALT) from 115.9 (+/- 12.9) to 82.5 (+/- 10.6) u/l (p < 0.01), of gamma-glutamyltranspeptidase (gamma-GT) from 51.4 (+/- 9.3) to 41.3 (+/- 4.2) u/l (p < 0.02) and of total bilirubin (TB) from 0.76 (+/- 0.08) to 0.53 (+/- 0.04) mg/dl (p < 0.05). Alkaline phosphatase (AP) fell slightly from 143.4 (+/- 6.4) to 137.5 (+/- 7.8) u/l. There were no significant changes in MDA, Cu or Zn serum concentrations. These results show that IdB1016 may improve LFTs related to hepatocellular necrosis and/or increases membrane permeability in patients affected by CAH.