Numerous studies have documented a role for corticosterone in appetitive behavior, including caloric intake and dietary fat preference. In the present study, we have examined the mechanism(s) underlying modulation of dietary fat preference by corticosterone. The results of these studies show a) an increased fat preference with increased basal urinary output, or decreased stimulation of corticosterone output on fasting, b) elevation of fat preference following chronic, but not acute, hypercorticosteronemia produced by exogenous corticosterone administration, and c) emergence of hypercorticosteronemia prior to the development of increased fat preference in developing rats. These observations have led us to suggest that increased fat preference after chronic hypercorticosteronemia may be secondary to changes in the levels or actions of agents known to affect fat intake.