Twelve students with in apparent good health and fasting since the previous evening ingested 2 g of L-carnitine on one day and a placebo on another day in a single-blind trial. Six blood samples were taken during the 24 h following the ingestion. Their blood carnitine levels increased (the free form by 81%, and the total by 57%) to a maximum at about 3.5 h and then slowly decreased. Twenty-four hours after ingestion, blood carnitine concentrations had still not returned to their initial levels. In the time interval where the decay curve approximated a single exponential, the half-life of the carnitine appeared to be of the order of 15 h. During the 24 h after the administration of the 2 g of L-carnitine, 7% +/- 1% of it was eliminated in the urine. This work suggest that the daily administration during a long period, of 2 g of L-carnitine guarantee in a healthy subject blood carnitine concentrations superior to the normal levels. Its remains to determine if the dose is sufficient in the case where L-carnitine is given to ameliorate a primary or secondary lack of carnitine, or to lower a high level of lipids in blood.