In a cholestatic infant showing hypoglycemia and cardiac failure, non-ketotic medium-chain dicarboxylic aciduria was disclosed by urinary organic acid analysis. As urinary excretion of long-chain fatty acids was also increased, a defect in beta-oxidation of long-chain fatty acids appeared likely. To try to improve this abnormality, carnitine supplements were given, which led to the complete resolution of clinical and laboratory abnormalities. This is the first reported case of a cholestatic infant who responded to carnitine supplementation. Deficiency of carnitine palmitoyl transferase was suspected as the underlying cause.