Platelet concentrate is used to restore and maintain hemostasis in patients with a reduced number or activity of platelets. Platelet concentrate changes its properties when stored, which leads to a weakening of the therapeutic effect, as well as the occurrence of transfusion side effects. One of the processes that alter platelet concentrates during storage is the secretion of several types of membrane vesicles. Despite the fact that platelet-derived membrane vesicles affect homeostasis and transmit signals of intercellular communication, mechanisms of their formation, features of regulatory activity and molecular composition are still poorly understood. In this paper, the results of analysis of CD42b and CD9 membrane proteins expression in platelets and platelet-derived membrane vesicles during platelet-concentrate storage are presented. Populations of membrane vesicles of different sizes were isolated from the platelet concentrates and characterized. Aggregation and morphological alteration of platelets are observed during storage; the protein composition of platelets, as well as membrane vesicles, changes, and there is a significant increase in the levels of CD42b and CD9 proteins in fractions of membrane vesicles. The results obtained indicate that platelet concentrates contain different populations of membrane vesicles, the molecular composition of which varies during storage.