ESR spectroscopy was used to investigate the production of reactive oxygen radicals in adriamycin (ADM) and its iron complex. The results showed that ADM-Fe(3+) induced the production of oxygen radicals more efficiently than ADM. The damage of BSA mediated by ADM or ADM-Fe(3+) was investigated by measuring the increase of reactive carbonyl content and the decrease of the fluorescence intensity of the Trp residue. It was shown that the damage of bovine serum albumin (BSA) was dependent on the time and on the concentration of ADM or ADM-Fe(3+). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that BSA was not cross-linked nor fragmented by the effect of ADM or ADM-Fe(3+). It was also found that oxygen radical scavengers could inhibit the damage of BSA induced by ADM or ADM-Fe(3+), suggesting that ADM or ADM-Fe(3+) induced protein damage via the oxygen radicals produced in the reaction.