To clarify the relationship between vestibular and visual (optokinetic) stimuli in normal children, we investigated the vestibulo-ocular reflex (VOR) and visual VOR (VVOR). The subjects were 20 healthy children aged 3-6 years and 24 healthy adults aged 21-29 years. The VOR gains and phase were measured under two visual conditions: with eyes open in complete darkness and with eyes open in a lighted optokinetic drum. In both visual conditions, phase did not significantly differ between children and adults. In the dark, children presented a significantly larger gain than that of adults. In the optokinetic drum, however, the gain values of the children were almost the same as in adults. We suggest that the large VOR gain values of children may be due to immaturity of the inhibitory regulation system of the VOR.