Major concern has emerged about the possible long term adverse effects of glucocorticoid treatment, which is frequently used for the prevention of chronic lung disease in preterm infants. Here we show that neonatal glucocorticoid treatment of rats increases the severity (p≤ 0.01) and incidence (p≤ 0.01) of the inflammatory autoimmune disease experimental autoimmune encephalomyelitis in adult life. In search of possible mechanisms responsible for the increased susceptibility to experimental autoimmune encephalomyelitis, we investigated the reactivity of the hypothalamo-pituitary-adrenal axis and of immune cells in adult rats after neonatal glucocorticoid treatment. We observed that neonatal glucocorticoid treatment reduces the corticosterone response after an LPS challenge in adult rats (p≤ 0.001). Interestingly, LPS-stimulated macrophages of glucocorticoid-treated rats produce less TNF-α and IL-1β in adult life than control rats (p< 0.05). In addition, splenocytes obtained from adult rats express increased mRNA levels of the proinflammatory cytokines IFN-γ (p< 0.01) and TNF-β (p< 0.05) after neonatal glucocorticoid treatment. Apparently, neonatal glucocorticoid treatment has permanent programming effects on endocrine as well as immune functioning in adult life. In view of the frequent clinical application of glucocorticoids to preterm infants, our data demonstrate that neonatal glucocorticoid treatment may be a risk factor for the development of (auto) immune disease in man.