The autonomic sympathetic adjustments to sustained handgrip, upright tilt, and the Valsalva maneuver, were tested in a total of 52 patients, 26 with labile and 26 with fixed essential hypertension. Sustained handgrip (SHG) increased arterial pressure, heart rate (HR), cardiac index (CI), and tension time index (TTI) (p less than 0.01), but had no effect on total peripheral resistance index (TPRI) and left ventricular ejection rate index (LVERI) in either group of patients. The response to upright tilt and the Valsalva maneuver was different in the two groups. Upright tilt in labile hypertensives increased diastolic arterial pressure (DAP), mean arterial pressure (MAP), HR, and TPRI (p less than 0.001), and decreased CI, stroke index (SI), and LVERI (p less than 0.01), and had no effect on systolic arterial pressure (SAP). In fixed hypertensives, it decreased (SAP, MAP, CI, SI, and LVERI (p less than 0.001), increased HR (p less than 0.01), and had no effect on DAP and TPRI. The diastolic pressure overshoot of the Valsalva maneuver was attenuated in fixed hypertensives compared to labile hypertensives (P less than 0.001). Also, when the percent changes from control in diastolic and mean arterial pressure, heart rate, and total peripheral resistance index after sustained handgrip and upright tilt between the two groups of patients were compared, only upright tilt brought out the differences between the two groups. The results of this study indicate that upright tilt and the Valsalva maneuver are better predictors of autonomic function in hypertension than the grip test.