Platelet GPIa/IIa receptors play key roles in the adhesion of platelets to collagen during the formation of coronary thrombosis. The C807T and HPA-5 polymorphisms of the gene for GPIa define three distinct alleles of GPIa which are associated with the surface expression of the protein in an allele-dependent fashion. Significance of these polymorphisms in victims of sudden cardiac death (SCD) was studied in Helsinki Sudden Death Study (HSDS) comprising 700 autopsied middle-aged Caucasian Finnish men with 288 SCD victims and 84 men with fatal acute myocardial infarction (AMI). The high-expression A1 allele was found in 36.6% of control men as opposed to 38.0% of all SCD victims and 36.9% of men with fatal AMI (P>0.4). The high-expression A1A1 genotype was found in 11.9% of men with fatal AMI and 10.0% of controls as opposed to the low-expression A2A2 genotype which was found in 29.8% of men with fatal AMI and in 31.2% of controls (OR 1.2, P>0.3). Age group (under/over 55) had no effect on the results. Our results do not support an effect of the GPIa haplotype on fatal coronary events among middle-aged men.