Aging is associated with an increased susceptibility to infections and chronic inflammatory diseases. This might be caused by dysregulations of the endocrine system with increased activity of the hypothalamus-pituitary-adrenal (HPA) axis and decreased levels of sex steroids. Therefore, we investigated the stress-response of the HPA axis and glucocorticoid (GC) sensitivity of pro-inflammatory cytokine production in elderly men, compared to testosterone-treated elderly men and young controls. Stress-induced increases in cortisol did not differ significantly between experimental groups (F=2.10; p>0.10), but GC sensitivity increased significantly in young controls and testosterone-treated elderly men, while a decrease was found in untreated elderly men (F=5.28; p<0.01). We conclude that the increase in GC sensitivity after stress serves to protect the individual from detrimental increases of pro-inflammatory cytokines, a mechanism that is disturbed in elderly men and partly restored by testosterone treatment.