Mean arterial blood pressure, heart rate, and cardiac output were monitored at rest and during exercise of two grades of severity in conscious dogs under control conditions and after progressive interruption of the baroreflexes. Aortic arch denervation and vascular isolation and pressurization of the carotid sinuses were used to interrupt arterial baroreflexes. Subsequent interruption of cardiopulmonary afferents was produced by acute bilateral cervical vagotomy. The results indicate that 1) with the cardiopulmonary receptors alone operative, the arterial blood pressure response to exercise is abnormal, 2) cardiopulmonary receptors do not contribute to the moment-to-moment modulation of arterial pressure, and 3) the carotid sinuses, aortic arch, and cardiopulmonary receptors are all involved in determining the mean level of arterial blood pressure. It is concluded that vagally innervated cardiopulmonary receptors do not have a significant role in regulating arterial blood pressure during exercise but are involved in establishing the general level of arterial blood pressure.