Aim: To determine the secretion of corticosterone (CCS) both in vivo and in vitro during different intervals after orchidectomy in male rats. Methods: Three- and 12-month-old rats had been orchidectomized 0, 3, 6, or 9 months before decapitation. Results: Orchidectomy increased the concentrations of plasma CCS, the basal release of CCS, and the adenosine 3′, 5′-cyclic monophosphate (cAMP) production in rat zona fasciculata reticularis (ZFR) cells. The forskolin/3-isobutyl- l-methylxanthine-stimulated releases of CCS and cAMP production by ZFR cells were higher in rats with chronic hypogonadism. The CCS release from ZFR cells of orchidectomized rat was not altered by 8-bromo-cAMP treatment. Orchidectomy enhanced the stimulatory effect of deoxycorticosterone on CCS release in ZFR cells. Conclusion: These results suggest that orchidectomy-related increases of CCS secretion in rats are associated with an increase of adenylate cyclase activity, cAMP generation, and 11-β-hydroxylase activity in ZFR cells.