Recent official surveys have shown that 30% of all patients are given barbiturates and 40% tranquilizers by the medical administrations. So we have to expect that more than half of the adult population take these drugs in a more or less uncontrolled manner. General cautions of the producers concern only the possibly affected psychological reactions, for instance in driving a car or occupational situations. Our aim was to find out if there might be any influence on the sensory organ itself, especially on the retinal function, and to prove it by the ERG. Starting such investigations, we prefer to use animal experiments (cats) for several reasons- drug administrations to healthy volunteers for experimental reasons only can be avoided and not so much attention has to be paid to some restrictions with regard to the dosage, even in case of repeated administration. In pharmacological experiments on the ERG a greatmany physiological parameters have to be observed, e.g. blood pressure, heart rate, respiration, body temperature etc., because we know that the b-wave is very sensitive to the general physiological condition. To get statistically évaluable results very long lasting experiments of several hours and an optimal signal-to-noise ratio are necessary.