The behavior of electroretinographic potentials during the course of dark adaption has been studied after different preadaptation conditions. After preliminary dazzling with 1,500 apostilb (asb [ = 150 ml]), the electroretinographic curve was determined in darkness immediately after dazzling, after 15-minute preadaptation to an ambient photopic illumination of 15 asb ( = 1.5 ml), and after 15 minutes in complete darkness after dazzling. The results clearly show that the oscillatory potentials are materially influenced by the different preadaptation conditions. We conclude that the results support the hypothesis of the dependence of oscillatory potentials on retinal photopic function.