We studied the lipid transfer protein (LTP) activity in 23 men with old myocardial infarction (OMI) and 25 outpatients without ischemic heart disease as the control. LTP activity was measured according to Albers' method. Lipoproteins were fractionated by ultracentrifugation, and the lipids were measured by an enzymatic method. Apolipoprotein levels were measured by the TIA method. Compared with control plasma, OMI plasma showed significant decreases in HDL-C (p=0.0003) and Apo-A1 (p=0.0002) and significant increases in TG (p=0.0070), VLDL-C (p=0.0022) and Apo-B (p=0.0070). There was a significant increase in LTP activity in OMI plasma (p=0.0157). LTP activity was negatively correlated with HDL-C (r=-0.3384, p=0.0247), Apo-A1 (r=-0.3969, p=0.0084) and the HDL-C/HDL-TG ratio (r=-0.4352, p=0.0025). From these results we concluded that in patients with OMI, high LTP activity may lead to decreased plasma HDL-C and changes in HDL composition.