Microparticles (MP) are shed membrane vesicles released by various cell types following apoptosis or activation. MP circulate in human plasma and also accumulate in atherosclerotic lesions. A growing body of evidence has highlighted their involvement in inflammation, angiogenesis, coagulation, and the regulation of vascular tone. MP may therefore contribute to the initiation and development of atherosclerosis and its complications. Plasma MP originate from platelets, leukocytes, erythrocytes, and endothelial cells, and their levels increase in patients with cardiovascular diseases; specific cardiovascular medications also affect plasma MP levels. Most recent data suggest a potential prognostic role of circulating MP for identification of subjects prone to develop cardiovascular complications.