The authors studied eye movement responses to loud (110dB) clicks in 4 patients with Tullio effect due to superior semicircular canal dehiscence and in 9 normal subjects, by averaging the electro-oculogram. All 4 patients had small (0.1-0.3 deg) but easily reproducible vertical vestibulo-ocular reflex eye movement responses to the clicks. Normal subjects had responses that were at least 10 times smaller. The click-evoked vestibulo-ocular reflex test is a simple, robust way to screen dizzy patients for symptomatic superior semicircular dehiscence.