MAIN RESULTS: In total, 31 heterogeneous trials including 1690 participants with patellofemoral pain are included in this review. There was considerable between-study variation in patient characteristics (e.g. activity level) and diagnostic criteria for study inclusion (e.g. minimum duration of symptoms) and exercise therapy. Eight trials, six of which were quasi-randomised, were at high risk of selection bias. We assessed most trials as being at high risk of performance bias and detection bias, which resulted from lack of blinding.