It is clear that accelerated atherosclerosis and its clinical consequence cardiovascular disease is a major risk to long-term survivors on chronic hemodialysis. Several risk factors for this complication have been proposed.In the present study we focused the interest on the possible relationship between the plasma lipids, especially high density lipoprotein cholesterol (HDL-C) and ischemic heart disease (IHD). Studies were carried out on 36 patients undergoing maintenance hemodialysis (20 males and 16 females), ranged from 39 to 72 years of age.Nineteen of them (53%) had IHD, showing much higher incidence of the complication than for normal and hypertensive subjects of comparable age. When compared with the same age and sex, the HDL-C levels were significantly lower in the dialysis patients (DP) than in healthy subjects (p<0.001). Among the DP, subjects with existing clinical IHD had significantly lower levels of HDL-C than those without IHD (p<0.01). On the contrary, there was no significant relation between total cholesterol (TC) levels and incidences of IHD in the DP. TC-HDL-C/HDL-C(β/αC) ratios were higher in the DP than in the normal subjects, but the significant difference of these ratios was recognized only in females (p<0.05). Among the DP, the β/αC ratios were significantly higher in the patients with IHD than those without that (p< 0.001).The results suggested that the reduced serum HDL-C concentrations and the increased β/αC ratios might be the most important factors for the development of atherosclerosis, and hence of IHD, although DP were subject to a number of other cardiovascular risk factors such as hypertension, hyperuricemia, glucose intolerance, secondary hyperparathyroidism and others.The HDL fraction is considered to include the preferential substrate lipoproteins for lecithin cholesterol acyl transferase (LCAT) in plasma. However, there were no consistent correlations between the lipid concentrations in the HDL fraction and the LCAT activities in plasma.The plasma LCAT activities were positively correlated to the serum triglyceride, phospholipids and free cholesterol levels in the DP.