The present study assesses the biomechanical effectiveness of the Boston brace on a group of 14 patients with adolescent scoliosis. Interface pressure measurements were performed at the appropriate compression pads within the brace when it was first applied and on two further sessions within the 6-month period of brace treatment. A corresponding series of Cobb angle measurements also were performed. Mean values of total force exerted through the brace of 58 +/- 18 N were associated with an initial curve correction of 37 +/- 21%. This mean force level was maintained throughout the study, although the mean curve correction at 6 months had reduced to 15 +/- 14%. In addition to biomechanical parameters, factors relating to the nature of the individual curve were important in determining the overall effectiveness of the Boston brace system.