A series of 23 patients with paralytic brachial neuritis is reviewed. It is noted that there is a higher incidence in men than in women; etiology is unknown. This syndrome is not uncommon and frequently is diagnosed incorrectly. The onset is sudden, with severe pain along one side of the shoulder girdle, followed in a few hours or days by atrophic paralysis of muscles over the affected shoulder; the disorder is occasionally bilateral. The pain usually subsides within a few days or weeks, but the paresis persists for months or even years. Prognosis is usually satisfactory for the return to good function, but recovery for customary physical activities is usually slow. Mild sensory loss may be present.