Platelet adhesion to and activation by exposed subendothelial collagen plays a critical role in normal haemostasis and pathological thrombosis. Recent advances in elucidating the mechanisms underlying platelet–collagen interaction support a ‘two-site, two-step’ model. Direct platelet binding to integrin α2β1 mainly sustains adhesion and allows recognition of glycoprotein VI. The latter interaction is responsible for characteristic intracellular signalling events leading to p72Syk and PLCγ2 activation. The present review describes the known collagen receptors on platelets and discusses the current understanding of signal transduction promoted by collagen.