To elucidate autonomic function in individuals with severe motor and intellectual disabilities, we evaluated sympathetic skin response in 14 patients with severe motor and intellectual disabilities. The results of sympathetic skin response were compared with those of patients with mild or moderate motor and intellectual disabilities who could walk and had an intelligence quotient > or = 35 (7 cases) and neuromuscular diseases (3 cases). No sympathetic skin response was recorded in patients with severe motor and intellectual disabilities, whereas all patients with mild or moderate motor and intellectual disabilities defined above and neuromuscular diseases showed sympathetic skin response. The results suggested that all patients with severe motor and intellectual disabilities had autonomic dysfunction, and sympathetic skin response can be a useful test that can evaluate autonomic function in patients with severe motor and intellectual disabilities.