Patients with hyperdynamic symptoms of a severe sepsis and patients after severe head injury show remarkable metabolic disturbances, which become apparent in a persistent catabolic stage. This was found in 17 septic patients (group I) and in 20 patients after severe head injury (group II), who were studied for a period of 10 days. During this time the urea production rate (UPR) and the catabolic index (CI) were measured. After a preliminary period of 5 days a stimulation test of hGH secretion using arginine was carried out to estimate the secretion of hGH, insulin and blood glucose. After this stimulation test a substitution therapy using 0.05 IU/kg B.W. i.m. hGH (Crescormon, Kabi Vitrum, München) was applied to 11 patients in group I (group Ia) and in 8 patients in group II (group IIa) who were then compared with patients without substitution therapy. The mean values of hGH basic secretion were the same in all groups and were within the normal range. 30 min after stimulation it was possible to identify a distinct response pattern; 90 min after stimulation there was no significant response. All groups showed significantly elevated levels of insulin; no further elevation after stimulation was observed. The blood glucose levels in all groups remained within the normal range at all times. All the groups were similar regarding behavior of the investigated parameters.(ABSTRACT TRUNCATED AT 250 WORDS)