Platelet glycoprotein IIb/IIIa may be involved in the pathogenesis of myocardial infarction as the key element in platelet aggregation and as the binding site of lipoprotein(a) to platelets, inhibiting plasminogen binding and activation. Recently, a strong association between the P1A2 polymorphism of the glycoprotein IIIa gene and acute coronary thrombosis has been reported. although this has not been confirmed. In an associated study, we determined plasma lipoprotein levels, the apo E genotype and the P1A genotype in 250 males under 55 years with myocardial infarction and they were compared with 250 age- and sex-matched controls. Patients showed an over-representation of the epsilon3/4 genotype with respect to the control group. We found that there were no differences in the allelic frequency of P1A2 between case patients and age-matched controls (chi2 = 0.05, P = 0.92) and that subjects bearing the P1A2 allele showed higher plasma lipoprotein(a) concentration than p1A1/P1A1 individuals. Therefore, in this population there is no association between carriage of p1A2 allele and increased risk of myocardial infarction but the carriage of P1A2 is associated with higher plasma Lp(a) concentration.