The lipid-reducing effects of a new fibric acid derivative (beclobrate, 100 mg/day), L-carnitine (15 mg/ kg b.w. thrice weekly i.v.), and the administration of both drugs were investigated in hyperlipidaemic haemodialysis patients. Beclobrate significantly decreased serum triglycerides, cholesterol and phospholipids. This was predominantly due to reducing the VLDL fraction. Plasma values of beclobric acid remained within the therapeutic range throughout the study. Carnitine administration did not influence plasma beclobric acid values. On the other hand, beclobrate caused a significant decrease of serum values of short-chain and long-chain carnitine esters in patients treated with both drugs. Carnitine therapy showed a tendency to affect total triglycerides, cholesterol, or phospholipids. However, carnitine antagonised the VLDL-reducing effect of beclobrate when both drugs were combined. Our data demonstrate a potent lipid-reducing effect of the new fibric acid derivative (beclobrate) in haemodialysis patients. Single-dose drug administration resulted in therapeutic beclobric acid plasma values and did not give evidence for drug accumulation. Careful monitoring of serum lipids is recommended for haemodialysis patients on carnitine therapy treated with lipid-reducing substances of the 'fibrate' group.