The effect of adaptation to short flashes of light on the oscillatory potentials and the slow potentials (a-and b-wave) of the human ERG as well as the effect on adaptometric visual threshold in response to a series of three flashes were studied. The total energy and the dominant frequency of the oscillatory potentials in response to the third (stimulus) flash were calculated by a combined impulse response and Fourier analysis when the interval between the flashes changed and the intensity of the first two (conditioning) flashes varied. When recorded in response to flashes given at long intervals or conditioning flashes of low intensity the visual threshold recovered to the scotopic branch of the dark adaptation curve and the oscillatory potentials showed a low energy and high frequency (around 150 Hz). On adaptation to flashes at shorter intervals and more intense conditioning flashes [above the threshold for the appearance of the photopic b-wave in response to the second (conditioning) flash], resulting in the recovery of the visual threshold to the photopic branch of the dark adaptation curve, there was an increment of energy and the frequency changed to 105-110 Hz.The slow potentials (a-and b-wave) and the oscillations were differently affected by adaptation to light by previous flashes. The oscillatory potentials showed a 10-fold gain in energy, whereas the amplitudes of the slow potentials were slightly reduced (about 10 Oio). The oscillatory potentials were optimally recorded in the mesopic range