The pendular rotation test (non-damped) in a head-tilted position, 60° backward and then rotated 45° either to the right or left, was performed in 6 patients with benign paroxysmal positional vertigo. The stimulus mode was amplitude = 360°, frequency = 0.1 Hz, and the maximal speed = 114°/s. By this test procedure, it was possible to evaluate the excitability of vertical semicircular canals. Using an infra-red CCD camera and a personal computer system, the evoked nystagmus was analysed. A statistically significant difference (p < 0.05) in the maximal slow-phase eye velocity of vertical nystagmus was found between those from the anterior semicircular canal and those from the posterior semicircular canal. The excitability of the posterior semicircular canal in the affected ear was found to be lower than that of the anterior semicircular canal.