To define the role of the rostral pons in the control of release of ACTH, we stimulated electrically (30 sec, 200 μA, 50 Hz) 128 sites in the dorsal rostral pons of 20 cats anesthetized with chloralose/urethane. Responses of arterial pressure to electrical stimulation were prevented by lesions placed previously in the medulla. Plasma concentrations of ACTH were measured by radioimmunoassay. Active areas consisted of three regions: 1) lateral inhibitory: Locus subcoenileus and anteroventral locus coeruleus (mean ΔACTH: -189, -164, -145 pg/ml at 1.5, 3.0 and 6.0 min respectively, P < 0.01); 2) intermediate facilitatory: Principal locus coeruleus and lateral ventral tegmental nucleus (mean ΔACTH: +81, +68, +37 pg/ml; P < 0.05); and 3) medial inhibitory: Dorsal tegmental nucleus, dorsal raphé and medial ventral tegmental nucleus (mean ΔACTH; -211, -212, -115 pg/ml; P < 0.01). The former two areas receive direct projections from medullary neurons activated or inhibited by atrial stretch, and, in turn, give rise to adrenergic and cholinergic projections to the medial hypothalamus. Since the release of ACTH is inversely correlated with right atrial stretch, the results suggest that the lateral inhibitory area and the intermediate facilitatory area are involved in mediation of changes in release of ACTH in response to hemodynamic changes. © 1976 by The Endocrine Society.