Dehydroepiandrosterone (DHEA) and DHEA sulphate (DHEAS) inhibit T-helper lymphocyte type 2 immune reactions and exert anti-inflammatory effects in some chronic inflammatory diseases. Both DHEA and, in particular, DHEAS levels are dramatically decreased in chronic inflammatory diseases whereas cortisol levels remain stable or are elevated. However, the time course of cortisol relative to DHEA production is not known. We tested whether administration of endotoxin to healthy male subjects can induce an early predominance of cortisol relative to DHEA and DHEAS. It is demonstrated that endotoxin induces a dose-dependent increase of cortisol in relation to DHEA (no effect at 0.2 ng endotoxin/kg body weight (b.w.), clear effect at 0.4 and 0.8 ng/kg b.w., p<0.05) and DHEAS (tested at 0.4 ng/kg b.w., P=0.014). The increase of cortisol relative to DHEA appears 4 h after endotoxin injection and 2 h after a strong increase of interleukin (IL)-6 relative to tumour necrosis factor (TNF). In addition, an increase of cortisol relative to 17OH-progesterone was observed. The ratio of serum IL-6/TNF was positively correlated with the ratio of serum cortisol/DHEA (R(Rank)=0.472, P=0.041) and serum cortisol/17OH-progesterone (R(Rank)=0.514, P=0.048). In conclusion, dissociation of cortisol relative to DHEA, DHEAS or 17OH-progesterone appears very early during a systemic inflammatory response which is associated with an increase of IL-6 relative to TNF. As in chronic inflammatory diseases, during an acute inflammatory response with endotoxin, these physiological hormone changes are probably necessary to achieve adequate cortisol levels at the expense of adrenal androgens.