The authors reported 17 cases of common form of juvenile amyotrophic lateral sclerosis (ALS), 14 cases with spastic paraplegia and peroneal atrophy, and 12 other cases belonging to one single family with spastic pseudo-bulbar paraplegia. The absence of sensory disturbances, the normal motor and sensory conduction velocities, the normal feature of sensory nerve biopsy allowed to include these 3 groups of patients in the frame of Juvenile ALS which is chronic and benign disease. The authors discussed these observations on the light of the literature data on familial spastic paraplegia and primary lateral sclerosis.