An operation for chronic prepatellar bursitis is described in which only the posterior wall of the bursa is excised, thus preserving, undamaged, healthy and normally sensitive skin. This procedure is easier and less traumatic than complete excision of the bursa and results in fewer complications. It is suggested that removal of tha anterior wall of the bursa results in unnecessary and harmful interference with the underlying skin. The operation described gives a good functional and structural result; leaving the anterior wall of the bursa does not predispose to recurrence.