Bacground and Objective: Foot orthoses are a common intervention for patients with patellofemoral pain syndrome but, limited information is available in the effects of foot orthoses on knee pain and function of athletes with patellofemoral pain syndrome. The aim of our study was to determinate the effects of foot orthoses on reducing pain and increasing function of athletes with patellofemoral pain syndrome who demonstrated excessive foot pronation. Materials and Methods: 418 female athletes between 15 – 35 years old in running, soccer, volleyball, fencing and mountain climbing were examinated. Among these athletes 25 subjects with patellofemoral pain syndrome had excessive foot pronation. The severity of pain was measured by VAS (visual analog scale) and their function were measured by KOOS (knee injury and osteoarthritis outcome score). Full length firm foot orthoses were given to athletes which at least 8 hours during the day was used. After 2 weeks: pain by VAS and function by KOOS were evaluated. After 6 weeks these variables were measured again. Results: The results of analysis of variance in repeated measures indicated a statistically significant improvement in pain by VAS after 2 weeks (p value=0.001) and after 6 weeks (p value=0.001). Improvement of function on KOOS were statistically significant at 5 subscales : reduction of symptoms after 2 weeks was not prominent but after 6 weeks was significant (p value=0.001) and reduction of pain after 2 weeks (p value=0.001), reduction of pain after 6 weeks (p value=0.001) and improvement of ADL after 2 weeks (p value=0.004) and after 6 weeks (p value = 0.001) and improvement of sport activities after 2 weeks (p value=0.012) and after 6 weeks (p value=0.001) and improvement in QOL after 6 weeks (p value=0.001). Conclusion: Our results confirmed a significant improvement in reducing pain and increasing function of female athletes with patellofemoral pain syndrome and excessive foot pronation after foot orthoses.