Eight preterm infants, five with postnatal asphyxia, as well as two hypotrophic neonates and one term infant with severe postnatal asphyxia (mean birth weight 2300 g) were fed, in addition to oral nutrition, partially parenterally with glucose solution and mother's-milk-adapted amino acid solution during their first three days of life. By increasing protein supplies with a parenteral share of more than 50% during the three days, the nitrogen balances were positive on all days, although the calories supplied were far below the postulated optimum. On days 2 and 3, nitrogen retention was about 60% of the supply. Every 4 hrs after discontinuation of the 16 hr amino acid infusion, the amino acid levels in the plasma were examined by column chromatography. The resulting mean values did not show any imbalances of amino acid homeostasis. The maximum mean loss in weight of the present groups was 4% of the birth weight during the first 10 days of life and thus equalled the loss in weight of normal healthy preterms. Clinical and chemical parameters did not reveal any disadvantageous side effects of partial parenteral nutrition.