Platelets exhibit membrane receptor proteins the structure of which has adapted, in the course of evolution, to halt hemorrhage. These receptors are also implicated in thrombosis, and their structural variability is likely able to account for part of the variability in intraindividual susceptibility to thrombotic events. This review offers a summary of current knowledge on the molecular structure and function of platelet membrane receptors, here studied also in relation to the variability of platelet function in the general population, with the aim of discussing possible implications for the atherothrombotic risk.