The authors report on their results of total parenteral nutrition (TPN) which was performed in a group of 11 comatose patients following elective neuro-surgery of different midline lesions (e.g. tumours, aneurysms of the anterior communicating artery). Carbohydrates were administered from day 1 postoperatively in a dose of 18-24 kcal/kg BW/day. Amino acids were given as a commercially available 12.5% solution (1.4-1.83 g/kg BW/day). Daily routine laboratory values were measured as well as levels of total serum protein, albumin, prealbumin, and retinol-binding protein. Free amino acids in plasma were measured on the day of operation and on day 3, 5, and 7 postoperatively. Renal nitrogen loss was high with maximal values up to 30 gm/day. By TPN cumulative nitrogen balance remained positive until day 2 and was reduced to -61.8 g at the end of the study period. Short-lived serum proteins remained normal. Free FAA's in plasma increased steadily with their highest levels on day 5 and 7 (twice the normal range). Besides slight elevation of liver enzymes and mild hyperglycaemia, no severe changes were observed in routine laboratory parameters. The authors conclude that severe catabolism is a common feature in comatose patients after elective midline surgery and is comparable to catabolism following brain injuries. TPN is well indicated in this group as it preserves visceral protein levels and reduces nitrogen loss without severe side effects.