The results of human and animal studies of the effects of lead absorption on sensory evoked and slow brain potentials are reviewed. These studies of flash evoked potentials in rats produced conflicting evidence of increased and decreased latencies, decreased amplitude, and increased or decreased cortical excitability. Studies of slow wave voltage in children during sensory conditioning indicated a linear relationship to blood lead level in two studies, an effect that could not be replicated in an indendent sample of children. Results of a fourth study indicated that slow voltage measures were more sensitive to lead during active rather than passive conditioning. Conflicting evidence of lead effects on pattern-reversal visual evoked potentials in children was found in three studies. Evidence of increased latencies-of brainstem auditory evoked potentials at blood lead levels above 25/dl were reported in two studies.