Eighteen hyperlipidemic hemodialysis patients were treated with 1, 5, and 15 mg L-carnitine/kg body weight (each dose was given for three months) given intravenously at the end of the dialysis therapy. Low dose L-carnitine treatment caused an increase in plasma total carnitine (TC), short chain acylcarnitine (SCC), and long chain acylcarnitine (LCC). An increase in plasma free carnitine (FC) occurred only in the 10 responders who showed a significant decrease in serum triglycerides. Serum VLDL triglycerides, VLDL cholesterol and VLDL phospholipids also decreased in the responders compared to nonresponders. There was no difference in HDL- and LDL-lipoproteins in both responders and nonresponders. L-carnitine in doses of 5 or 15 mg/kg body weight caused markedly elevated plasma levels of all carnitine fractions but no further lipid lowering effect. Moreover, enhanced serum triglycerides were observed in some hemodialysis patients. Thirteen out of 15 patients displayed an increase of HDL triglycerides and 5, an increase of VLDL triglycerides. Our data suggest that low doses of L-carnitine are effective in treating hypertriglyceridemia in selected patients. Low dose L-carnitine also avoids unphysiological high plasma levels of carnitine and carnitine esters and prevents antiketogenic effects in hemodialysis patients.