A collision method in a single axon was used to determine the origin of 100 fasciculations in various lower motor neuron lesions. For 80% of the fasciculations, it was situated on the distal extremity of the axon regardless of the type of lesion, its duration, or the severity of the denervation. For several reasons, this proportion is underestimated. The fasciculations of distal origin were sometimes, associated with double discharges, the mechanism of production and clinical significance of which probably differ.