To elucidate the contributory role of heparin to abnormal lipid metabolism in patients on regular haemodialysis (RDT), six week haemodialysis without heparin was performed using gabexate mesilate in combination with low dose aspirin. Total cholesterol and beta-lipoprotein were significantly increased at the fourth week after the start of the study. No significant changes were observed in high density lipoprotein cholesterol, phospholipid, triglyceride, lipoprotein phenotype and post heparin lipolytic activity. Routine dose heparin in RDT might have a favourable effect on abnormal lipid metabolism by inducing post heparin lipolytic activity in circulating blood, not by reducing the lipid removing activity in peripheral tissues.