Introduction. In earlier papers (Aschan, Bergstedt, Goldberg, and Laurell 1955-1956, Aschan and Bergstedt 1956 and 1957, to be published) it was shown that intake of alcohol provokes nystagmus. This nystagmus is partly a vestibular positional alcohol nystagmus (PAN) partly an ocular alcohol gaze nystagmus (AGN). These two forms of nystagmus are of quite different origin and possess different properties; the vestibular PAN appears in two phases, the second one persisting for hours after all the alcohol has left the blood, while the ocular AGN appears only above a certain threshold concentration of alcohol in the blood. An important fact to be noted is that the nystagmus objectively recorded under identical experimental conditions in the same subject varies only slightly as regards time and intensity. It is thus possible to study the effect of different drugs, qualitatively as well as quantitatively, both in the individual subject and in different individuals.