Kennedy's syndrome is usually classified among the progressive spinal amyotrophies. Scarce reports suggest the involvement of the peripheral nerves. Five cases are reported here with a decrease of the sensory potential amplitude. A pathological study in 4 of these cases showed lesions of the sensory nerve. The notion of neuronopathy is discussed because it underlines the physiological unity of the cellular body and of the axon and the difficulty to separate the reciprocal damage in certain pathological cases. It would be excessive to equate clinical and experimental cases in which the onset of the disease involves either the cellular body or the axon.