Since prognosis of neonatal diseases, especially RDS, in premature infants is impaired by nitrogen imbalances, we compared the effect of 3 amino acid mixtures(AA) on nitrogen balance, blood glucose(BG), plasma insulin(IRI), human growth hormone(HGH), glucagon and cortisol. 3 AA-mixtures were supplied i.v. : A) AA/sorbitol/xylitol each 5g/100ml, B) AA 5g/100ml, C) AA 5g /glucose 10g/100ml. RESULTS: In all 3 groups nitrogen balance immediately became positive. BG showed a mild elevation in group A, no change in B and a sharp rise up to 180mg% after 60 min, in C. IRI corresponded well with BG in A and B. C showed an excessive IRI-rise(104 uU/ml after 60 min.). Glucagon was not affected in A and C. In B there was a rise up to 273pg/ml after 60min. HGH was well stimulated in all groups with an average maximum of 43ng/ml after 60 min. Cortisol showed mean levels of 6ug/100ml without significant change. CONCLUSION:AA-infusions and reactively high endog. HGH lead to pos.nitrogen balance. AA did not affect IRI, glucagon and cortisol reaction.