Cardiovascular morbidity and mortality in hemodialyzed patients are increased due to the frequently abnormal lipid metabolism. It has been reported that this abnormal lipid metabolism could be partially corrected by some highly permeable membranes, such as polysulfone or cellulose triacetate. We investigated the influence of 4 months of dialysis with a polyamide membrane upon the course of lipid parameters in 6 patients presenting a hypertriglyceridemia > 2 mmol/l while on bicarbonate dialysis with a cellulose membrane. Lipid parameters improved after 4 months of hemodialysis with a polyamide membrane. Serum triglyceride and cholesterol levels decreased, while HDL cholesterol and HDL levels rose significantly (p < 0.05). Apolipoprotein B decreased significantly (p < 0.05). Following heparin administration, lipoprotein lipase activity improved (p < 0.02), associated with a decrease apolipoprotein C3 (p < 0.05). The fractional clearance rate of triglycerides rose significantly (p < 0.01). The use of highly permeable polyamide membranes results in a significant improvement in lipid disturbances of dialysis patients due to an increased lipoprotein lipase activity, induced perhaps by the removal of circulating inhibitors such as apolipoprotein C3.