OBJECTIVE To examine the potentials evoked by rotatory stimulation, which we consider the optimal means of invoking angular acceleration and which may lead to clinical applications in patients with vertigo. MATERIAL AND METHODS Horizontal rotatory stimulation using a trapezoidal waveform was performed with 3 different angular accelerations (20, 15 and 10 degrees/s2) used sequentially, with alternating clockwise and counterclockwise stimulation, to normal subjects and a patient with bilateral loss of vestibular function. RESULTS It is likely that angular accelerations of < 20 degrees/s2 produce minor somatosensory effects. Clear potentials were evoked in 13/18 ears (72%) of the normal subjects with stimulation at an angular acceleration of 15 degrees/s2. No response was recorded in the patient with stimulation at 15 degrees/s2. CONCLUSION We suggest that an angular acceleration of 15 degrees/s2 is optimal for clinical examinations.