Oxidative stress caused by excessive accumulation of pro-oxidants and/or depletion of antioxidants, is an important pathogenic factor. Oxidative stress leads to oxidative modification of macromolecules. Proteins are a target for oxidizing agents. Of other antioxidants in human blood plasma, serum albumin is particularly interesting as a target for reactive oxygen species. In this brief review albumin is looked upon as a target for free radicals, an antioxidant, and a source of free radicals in its complexes with copper ions. Possible targets for free radicals in protein structure and the consequences of their exposure to free radicals attacks have been analyzed. The role of glycosylation in contributing to protein oxidative modification has been studied. The original experimental data on albumin structure changes in various models of oxidative stress obtained by a spectrofluorimetric method are pesented. Increased antioxidant properties of albumin modified in a physical model of oxidative stress (UV-irradiation) have been described.