Reactive oxygen species ( ROS) , which include superoxide anion ( O2. ) , hydroxyl radical (OH) , hydrogen peroxide (H2O2) , singlet oxygen ( 1O2 ) and nitric oxide (NO) are highly reactive particles. Can react with lipids, proteins or DNA , causing irreversible changes in the structure of these compounds. Platelets , like other cells , can generate ROS , which are drawn into the mechanisms of activation of these cells . There are several ways to manufacture platelet RFT . In cells stimulated with various physiological agonists ( thrombin, collagen) potential sources of reactive oxygen species are the processes related to the metabolism of arachidonic acid (involving cykloosygenazy or 12 -lipoxygenase ) , phosphoinositol metabolism and glutathione cycle . ROS are also generated by the activation of platelets, NADPH oxidase , xanthine oxidase , and NO synthase . Reactive oxygen species may act as second messengers in thrombin- activated platelets or collagen . This review article presents the role of ROS in platelets .