Oscillatory potentials (OP's) were recorded using constant energy stimulating from 2.5 J at different levels of adaptation from 400 to 30 fl, as well as pre-dark adaptation. O1, O2, and O3 regularly appear in the ascending branch of the b-wave complex, and after pre-dark adaptation the less differentiated O4 and O5 appear as well, exhibiting variable potental heights and durations as the dark time progresses. With intensive pre-light adaptation there is a relative reduction of potential, as is also true following weak prelight adaptation or dark adaptation; the culmination time in the former case being more rapid, and in the latter case slower. Good discrimination of the OP with a concurrent diminution in the amplitudes was only observed after a pre-dark adaptation.