Lipoprotein (a) [Lp(a)J is a macromolecular complex found in human plasma and is composed of 1 low density lipoprotein (LDL) particle to which 1 or more molecule of apolipoprotein (a) is covalently linked. Elevated levels of Lp(a) have been associated with acute myocardial infarction (AMI). In this study the serum levels of Lp(a) in patients with AMI compared with control subjects in Turkiye was determined. We determined serum levels of Lp(a) in 72 patients (47 men and 25 women) with clinically, electrocardiographically and biochemically documented AMI, and in 64 control subjects (28 men and 36 women) clinically free of cardiovascular, peripheral or cerebral arterial disease on the basis of history, physical examination and electrocardiographic criteria. Patients with AMI had higher Lp(a) levels than did control subjects (33.9 ±23.9 vs. 14.1 ± 11.1 mg/dl, p<0.0001). The prevalence of Lp(a) excess (defined as >90th percentile of controls) was 55% in patients with AMI. Lp(a) levels were not correlated with other lipid and lipoprotein parameters. Also there was no correlation between serum Lp(a) levels and age and gender of subjects. Our data indicate that Lp(a) is a risk factor for AMI, independent of other lipid and lipoprotein parameters.