All red wines tested in our study showed evident radical-scavenging properties. In particular the radical-scavenger efficiencies of these wines may be attributed, in a significant number at least, to their content of total phenols, and are affected by alcohol only in a marginal way. Furthermore, the antioxidant efficiency of red wines tested appears to be largely influenced by the proanthocyanidin level, with anthocyanins playing a minor role. Finally, ascorbic acid, thiol groups and SO2 (antioxidant compounds present in red wines especially as consequence of the wine-making processes) play only a minor role in the radical-scavenging power of the red wines under investigation. In conclusion, the present findings support the results from several experimental and epidemiological studies, suggesting that the supply of antioxidant phenols through a moderate daily consumption of red wines may provide additional protection against in vivo oxidation of cellular biomolecules.