A series of neurophysiological variables was measured for men occupationally exposed to lead. The results were related to the degree of lead exposure and to the concentrations of lead and zinc protoporphyrin in blood. A small but significant correlation was observed between lead exposure and motor and sensory conduction velocities in the lower limbs, the conduction velocities of slow motor fibers in the upper limbs, and also sensory nerve action potentials. It is suggested that a neurophysiological examination should be considered in the surveillance of the health of lead workers.