The effects of ethanol on the human standing potential (SP) were studied with a recently developed method, which allows direct SP recordings by means of a suction contact lens, temperature stabilized calomel electrodes and d.c. amplification. It is well known that the human SP oscillates with a frequency of about 2/hour in response to a sudden change in illumination. In the present paper marked cyclic variations of the SP, resembling damped oscillations, were provoked by a small oral dose of ethyl alcohol. A first maximum was reached after about 10 min. The difference in amplitude between the peak and the trough of the first oscillation was of the order of 4 mV. The oscillatory frequency was about 2/hour. The length of a cycle varied between 25 and 34 min in different volunteers, being fairly constant in the same subject on different occasions. The SP response to ethanol was similar both under scotopic and photopic conditions. The results correlate well with earlier findings of 2/hour oscillations in c-wave amplitude in response to ethanol, as may be expected considering the partly common origin of the c-wave and the SP.