The concentration of total carnitine in the blood serum of 15 newborns between days 5-21 of life was determined. The concentration of carnitine in low-birth-weight newborns is decreased in comparison with normal weight newborns; this deficiency may increase as a consequence of lack of carnitine provided with food or concomitant infection. The authors suggest that supplementation with carnitine be provided to this group of patients so as to prevent possible metabolic and clinical consequences.