• We have studied the influence of intravenously administered diazepam on the horizontal (HVOR) and vertical (VVOR) vestibulo-ocular reflexes of the rabbit. The HVOR and VVOR were evoked by sinusoidal oscillation of rabbits on a rate table (0.01 to 0.8 Hz, ± 10°), and eye movements were measured with an infrared light-projection technique. The gains of the HVOR and VVOR (evoked eye velocity/head velocity) were reduced by diazepam injections of 5 μg/kg. The dose required to produce a 50% reduction in HVOR gain was 500 μg/kg. The time required to reduce the HVOR gain to 50% of its maximal reduction at a dose of 400 μg/kg (0.4 Hz, ±10°) was 60 s. These data suggest that diazepam might be effective as an anti-motion-sickness agent.