Thiol compounds present in the cells can be divided into low molecular weight and protein . Protein thiol groups , derived from cysteine ​​, may be present as free thiols, disulfides and mixed disulfides in combination with a low molecular weight thiols : glutathione , cysteine ​​, homocysteine ​​, and ? - Glutamylocysteiną . Metabolic related reactions of thiols have an important role in platelet function , anucleate cells derived from megakaryocytes , and performing an important role in hemostasis . Various low molecular weight thiols ( glutathione , cysteine, cysteinylglycine , homocysteine ​​thiolactone and its ) and changes in the redox potential of blood platelets play a special role in the different stages of platelet activation , the exposure of cell surface receptors and signal transduction . Furthermore , on the outer surface of the platelet membrane protein disulfides present isomerase that is involved in platelet activation , including activation of the integrin ? IIb ? 3 and the formation of platelet aggregates . In the present review article describes the behavior of selected low molecular weight thiols ( glutathione , homocysteine ​​and homocysteine ​​thiolactone ) in platelets .