In 1968 we studied 215 middle-aged patients with adolescent idiopathic scoliosis, who were initially seen in our clinic from 1932 to 1948, and who were not surgically treated. Most patients led normally active and productive lives, worked, married, and engaged in activities little different from those of the normal population. Many reported back pain but usually it was of minimum non-limiting nature. Forty-five per cent of the patients had diminished vital capacities although only 2 per cent had more than slight dyspnea on exertion. The curves increased an average of 15 degrees after termination of trunk growth. The highest average increase was seen in thoracic curves measuring from 60 to 80 degrees at maturity. We found a death rate similar to that of the normal population.