Of 8 infants on parenteral feeding for surgical conditions 3 died but the causes were not related to the infusion technique. The other 5 gained weight satisfactorily and recovered. Of 2 infants of low birthweight one responded excellently to intravenous feeding and gained weight steadily. The other had respiratory distress from birth and died after 6 days. Before and after intravenous feeding values for amino acids in blood did not vary significantly from each other or from control values. During parenteral feeding there were significant increases in methionine, lysine, threonine, glycine, serine and leucine, in some to more than double the control values. In the infants of low birthweight only methionine values were high.There were high ammonia values in the fibrin hydrolysate given to the infants and this caused high values in blood in 3 infants. During feeding output of urine and blood urea N increased. There was an acceleration of the Krebs cycle, possibly due to excess ammonia in the hydrolysate. It was concluded that intravenous feeding should be made available to premature infants and those of low birthweight but it is necessary for the hydrolysate content to be revised and ammonia-free amino acid solutions made available.