The aim of the study was to describe the influence of posttraumatic calorie and nitrogen (N) supply upon the cumulative N-balance by analyzing the literature of the past 18 years. Three groups of patients were formed, in which nutritional therapy was performed following trauma of differing severity: (1) patients following moderate trauma-N-losses 10-15 g/day; (2) patients following severe trauma--N-losses 15-20 g/day; and (3) polytraumatised patients--N-losses more than 20 g/day. The data gained for the calorie and N-supplies as well as for the N-balances in each group of patients served as a basis for the calculation of regression analyses of higher order; in these the cumulative N-balance was regarded as a function of the calorie and the N-supply: NBcum = f (C, N) Whilst for the group of polytraumatized patients only statements for a nutrient supply of about 20-30 kcal/kg BW/day and 0.2-0.3 g N/kg BW/day are possible, due to the limited data available, general statements about the different influence of calorie and N-supply can be made for nutritional therapy after moderate and major trauma; the calculated functions reveal that the N-supply influences the N-balance decisively, whereas the calorie supply exerts only a slight N-sparing effect. The mathematically calculated optimum of the N-supply after severe trauma is 0.2 g/kg BW/day, corresponding to an amino acid supply of 1.25 g/kg BW/day.