Seventy-eight unfused patients with idiopathic scoliosis were followed from skeletal maturity over a mean period of 17 years (range 10 to 27 years) with a mean age at follow up of 33.7 years. The following aspects were investigated: curve deterioration, back pain incidence, and psychosocial details. There was considerable variation in the progression rate of similar deformities but on average significant deterioration occurred when the Cobb angle was over 55 degrees with a maximum deterioration approaching 1.5 degrees per year in the thoracic curves between 90 degrees and 100 degrees mature Cobb angle. Thoracolumbar and lumbar curves were slightly more benign with a maximum progression rate of about 1 degree when the mature angle was 80 degrees to 90 degrees. The thoracic component of double curves progressed least. Rotation increased in proportion to the Cobb angle progression except in some lumbar curves where lateral subluxation occurred with a disproportionate amount of rotation. The incidence of back pain in relation to pain in the general population and in fused patients remains uncertain. Eighty-two percent of patients had married and 87% had job satisfaction; 10% received treatment for depression.