Neurootological research demonstrated significantly different vestibulo-ocular reactions by infants and young children as compared to adults. Neurohistological research has demonstrated that the vestibular apparatus is developed by birth and therefore should be fully functional. Fifty full-term and healthy infants and children between 9 days and 24 months of age were placed on an electrically controlled rotating chair in order to determine the functional development of the vestibular system. The rotational test program consisted of a supraliminal acceleration stimulus of 3 degrees/s2, a constant rotation at 90 degrees/s for 3 minutes, and a final abrupt deceleration stimulus. The frequency and amplitude of the per- and post-rotatory nystagmus reaction were analysed from the electronystagmogram. The nystagmus frequencies demonstrate a low level in the first month. The per- and post-rotatory deviate clearly from each other in the following months. The amplitude values also start out low in the first month then climb thru the 7th month and finally stabilize or drop slightly in both the per- and post-rotatory phases. The accumulated results will be discussed and typical examples will be demonstrated.