In a prospective study 60 consecutive patients underwent a distal iliotibial band transfer for anterolateral rotatory instability. A knee function score was obtained prior to operation and 17 and 40 months after operation. The maximum score possible was 100 points. Patients with scores greater than 77 were rated as good/excellent. The mean preoperative score was 59.3 points. At 17 months the score was 88.0, a significant improvement, and at 40 months it had dropped significantly, to 73.1. The decrease in score was due mainly to increasing symptoms of instability and pain. At the 17-month follow-up examination, 80% of the patients were stable, but at 40 months only 42% remained stable. The initial results were encouraging, but at 40 months the distal iliotibial band transfer did not function satisfactorily. The best results were obtained in patients in whom symptoms of instability were initially moderate.