Data extracted from 7 RCTs (n=626) was analyzed to evaluate the role of quadriceps muscle-strengthening exercise in the treatment of patellofemoral pain syndrome (PFPS). 3 studies (n=204) compared quadriceps muscle-strengthening exercise against advice and information. 5 studies compared quadriceps muscle-strengthening exercise combined with other interventions, against advice and information or placebo. The evidence presented in this systematic review indicated reduced pain and improved function associated with quadriceps muscle-strengthening exercise (alone or combined with other interventions) when compared against advice and information and/or placebo. Quadriceps muscle-strengthening exercise additionally demonstrated 12 month benefits for pain, but not for function.