Muscle sympathetic nerve activity (MSNA) is altered by stimulation of the vestibular system. Studies indicate that the otolith organs mediate increases in MSNA when engaged by head-down rotation (HDR). These findings are important with regards to postural blood pressure regulation on earth and post-spaceflight orthostatic intolerance. It is currently unknown if nongravitational activation of the otolith organs can mediate increases in MSNA. One method believed to stimulate the otolith organs is ultrasonic bone stimulation (UBS) of the mastoid. To test the hypothesis that UBS can augment MSNA we measured leg MSNA, heart rate, and arterial blood pressure during gravitational stimulation of the otolith organs by HDR and during stimulation of the mastoid via UBS in 14 healthy subjects (4 men and 10 women; age: 25 ± 4 yr; BMI: 24 ± 4 kg/m2). UBS of the mastoid elicited a significant increase in leg MSNA (3 ± 1 bursts/min, 31 ± 10% total activity; P < 0.05). This increase in MSNA via UBS was comparable to HDR (4 ± 1 bursts/min, 35 ± 8% total activity; P < 0.05). UBS of the clavicle (n=10), which served as a control, did not increase MSNA. In all studies, HDR and UBS did not change heart rate or mean arterial blood pressure. These results indicate that UBS stimulation can elicit sympathetic outflow and may assist in maintaining peripheral resistance and arterial blood pressure during orthostatic challenges.