Three male monkeys (Macaca mulatta) were operantly conditioned to raise and lower systolic blood pressure (SP). All animals were trained in three stages: first to lower, then to raise systolic pressure, and finally to alternate these two behaviors. All monkeys learned the task and performed reliably in all stages. Diastolic pressure (DP) usually paralleled systolic pressure but changed much less than SP. Heart rate (HR) always fell below baseline in lowering sessions, and in two of the three animals during raising sessions as well. These findings support our earlier results which showed that monkeys could learn to control heart rate. This animal model should permit detailed studies of the hemodynamic mechanisms mediating learned control of systolic pressure.