Platelet adhesion and aggregation play key roles in initiating coronary thrombosis and acute coronary syndromes. During the last decade platelet glycoprotein Ia and IIIa polymorphisms have been studied intensely in order to clarify their contribution to the thrombotic process and moreover their role in acute coronary syndromes. Studies examining these polymorphisms have been inconclusive and often controversial. Polymorphisms in the glycoprotein Ia seem to increase the risk for acute coronary events in younger persons and especially in the presence of other risk factors. The correlation of the Leu33Pro allele of platelet glycoprotein IIIa regarding platelet thrombogenicity is strong but it does not seem to alter the thrombotic risk of the general population. In conclusion, further studies need to elucidate their impact and the potential association with acute thrombotic events.