Specific in vitro glucocorticoid uptake and binding activity of spleen and splenic leukocytes were examined in adult (2- to 3-month-old) and senescent (24- to 28-month-old) male, adrenalectomized Sprague-Dawley and Wistar rats. No significant differences in these parameters were evident between young and old animals of either strain. Moreover, cortisol inhibition of [5-3H]-uridine uptake and the total number of glucocorticoid binding sites of spleen and its leukocytes were found to be similar in these two age groups. It was concluded that age has no effect on the glucocorticoid responsiveness of the splenic tissues of the two strains of male rats studied.