A 35-year-old man with a past history of achalasia developed progressive spastic tetraparesis, distal limb atrophy, dysarthria, and dysphagia. A clinical diagnosis of amyotrophic lateral sclerosis (ALS) was considered before neurophysiological investigation, which disclosed a polyneuropathy and a prolonged central conduction time. One year later, the patient developed dysautonomic symptoms. Following confirmation of adrenal insufficiency, a diagnosis of Allgrove syndrome was made. This is a rare case, and we emphasize its clinical similarity with ALS.