Although carnitine levels and carnitine therapy have been extensively studied in dialysis patients, the pathophysiology of L-carnitine is poorly understood. The usual therapeutic dose is 20-30 mg/kg, resulting in dramatic increases of circulating levels above the normal values. Guided by studies on its lipidic effect and by our experience of its action on haematocrit, we propose the use of 2-3 mg/kg of L-carnitine in future prospective studies.