The results of treatment of idiopathic scoliosis with a Milwaukee brace were studied in 133 patients (127 girls and 6 boys) whose ages ranged from 8 yr and 5 mth to 16 yr and 2 mth at the beginning of treatment. These 133 patients had 192 separate curves (119 right thoracic, 39 lumbar, 12 thoracolumbar, and 22 high left thoracic). Of these patients, 74 with 109 curves were followed for 5 yr or more after the brace was discontinued (average, 8 yr; range, 5 to 13 yr); 29 patients were treated surgically because of a poor response to the brace or progression of the curve; and 30 patients were lost to follow-up. More than 80% of the 74 patients followed for 5 yr or more showed some increase of their curves after the brace was discontinued. The average correction at follow-up compared with the original curve was 2 degrees for thoracic curve (range, -18 to 24 degrees) and 4 degrees for the thoracolumbar and lumbar curves (range, -11 to 17 degrees). The brace was more effective for curves of less than 40 degrees. More than one-third of the patients with curves of 40 degrees or more eventually required surgical treatment. Age, curve pattern, and status of the iliac and ring epiphyses did not correlate with the response to brace treatment. The best guideline for prediction of the results of brace treatment was the response of the curve to the brace, especially during the first year of treatment. If the curve is reduced in the brace to less than 50% of its initial measurement, there is a chance change of obtaining significant permanent correction.