Resveratrol (3,4',5-trihydroxystilbene) is a natural molecule with antioxidant action. It is also considered to be a molecule with antiplatelet, anticancer and anti-inflammatory action. The effects of trans-resveratrol on the reactive oxygen species (ROS) generation and thiobarbituric acid-reactive substances (TBARS) in blood platelets induced by endotoxin (lipopolysaccharide, LPS) or thrombin were studied in vitro. The production of superoxide radicals (O2.-) and other reactive oxygen species (H2O2, singlet oxygen, and organic radicals) in the presence of resveratrol was measured by a chemiluminescence method in resting blood platelets and platelets stimulated by LPS (0.3 microg/ 10(8) platelets) or thrombin (2.5 U/10(8) platelets). We have shown that resveratrol (6.25-100 microg/ml) inhibits chemiluminescence and generation of O2.- in blood platelets. It has an inhibitory effect on the production of ROS and TBARS in platelets caused by LPS or thrombin.