Seventy-eight consecutive patients with idiopathic scoliosis treated by Harrington instrumentation and spine fusion were allowed to walk shortly after operation, first in an underarm plaster cast for ten weeks and then in a canvas-front, hard-back Rohadur or Lexan brace until all external support was discontinued six months after operation. Sixty-four patients were followed for two years or more. Single thoracic curves, comprising almost half of the series, had an average final correction of 48 per cent, while all curves had an average final correction of 44 per cent. The average total loss of correction was 8 degrees, with approximately equal amounts lost in the first and second three months after operation. The incidence of pseudarthrosis was 1.5 per cent and the complications were minor. This series demonstrated that, for cooperative patients with idiopathic scoliosis of less than 90 degrees, the operative procedure and postoperative immobilization described can be expected to result in solid fusion without excessive loss of initial correction, pleasing cosmetic results, and less inconvenience to the patient because of decreased time in a plaster cast and early ambulation.