Objective: Reduced proprioception, Pain, changes in muscle activity patterns are sawn in PFPS. Balance is dependent on proprioception, visual, somatosensory and vestibular systems. So it is possible that balance be weaker in PFPS. The objectives of this study was the evaluation of the effect of patellofemoral pain on balance status of patients and comparing the balance between two groups.Anterior-Posterior, Medio-lateral and overall indexes were evaluated.

Materials & Methods: The research design was nonexperimental (case-control) study and the sampling was nonpropability (Sample of Convenience). We measured balance on a Biodex Stability System. Dynamic stability test was used for evaluation in two groups.

Results: Findings showed that balance indexes had difference between two groups.So that, overal index in close and open eye conditions had meaningful difference, but anterior-posterior and medial-lateral indexs did not show this difference.

Conclusion: Dynamic balance is weaker in patients with patello – femoral pain than others. Its main causes are Reduce of proprioception & changes in muscle activity patterns.