To examine steroidogenic responses of the different zones of the adrenal cortex to acute disease we determined the basal and adrenocorticotropin (ACTH)-stimulated levels of cortisol, dehydroepiandrosterone (DHEAS) and aldosterone in 16 infants aged 1-4 months with acute bronchiolitis. Fourteen of the infants were retested after recovery. During illness the mean basal levels of cortisol and DHEAS were twice as high as the levels after recovery (370 vs 180 nmol/l and 2.7 vs 1.3 mumol/l, respectively). The mean peak ACTH-stimulated levels of cortisol and DHEAS during illness were 1.5- and 2.5-fold higher, respectively, than the levels found after recovery. Although aldosterone secretion was stimulated > or = 3-fold by ACTH, illness was not associated with any change in aldosterone secretory capacity. The basal and stimulated levels of both cortisol and DHEAS during illness and after recovery were correlated significantly. Thus, the relative steroidogenic capacities for these two steroids were characteristic of the individual infant and showed constancy over a period of at least several weeks. While the levels of cortisol and aldosterone were not dependent on the age of the infants, both the basal and stimulated levels of DHEAS correlated strongly with age. We conclude that during acute disease the steroidogenic capacity selectively increases in the zones that secrete cortisol and DHEAS (only in infants < 3 months) but not in the zona glomerulosa that secretes aldosterone. The DHEAS response may be related to its putative effects to enhance immune responses.