L-Carnitine (oral route) signiñcantly corrects the muscle hypocontractility and hypoexcitability induced in the rat after 5 consecutive days of fasting. This effect is interpreted on the basis of the dual role of L-carnitine as cofactor in the transport of long-chain fatty acids into the mitochondria and as a detoxifying agent of intracellular acyl-CoA. The activity of L-carnitine is increased with the concomitant administration (oral route) of an equimolar dose of L-lysine. In the present experimental conditions, there is a threefold potentiation by comparison with L-carnitine alone. This result is discussed on the basis of the combined effects of an exogenous supply of L-carnitine and endogenous synthesis of L-carnitine from the L-lysine administered at the same time