Twenty-nine hemodialyzed patients with hypertriglyceridemia were given L-carnitine (20 mg/kg iv at the end of each dialysis) for 120 days and then placebo for the same duration in order to evaluate the lipid-lowering effects of the metabolite. A dramatic reduction in triglyceride levels was observed only in the group of patients (n = 12) with high basal triglyceride values, low levels of high-density lipoprotein-cholesterol, and with apoprotein A at the lower limit of normal range. During L-carnitine treatment these patients exhibited significantly increased high-density lipoprotein-cholesterol and apoprotein A. No rebound effects were observed. L-Carnitine did not provoke changes in the lipid parameters in the group (n = 17) with high basal triglyceride values, and normal high-density lipoprotein-cholesterol and apoprotein A. Hematocrit values increased in all the 29 patients during L-carnitine treatment. At the end of the experimental protocol, L-carnitine dosage was increased to 60 mg/kg iv (at the end of each dialysis) in four patients of the group of nonresponders and prolonged for 60 days. This produced a considerable reduction in triglyceride levels. The above results suggest that L-carnitine can be effective in the management of hypertriglyceridemia in the hemodialyzed patient especially when low high-density lipoprotein-cholesterol levels are present.