Background: Plantar fasciitis is the most common cause of heel pain but treatment remains empirical.Objective: To investigate the effect of interferon alpha 2b on pain, morning stiffness and tenderness of heels in patient with plantar fasciitis.Methods: Three hundred seventy six patients with plantar fasciitis enrolled in this study. The patients divided into two groups: Group one received interferon alpha 2b 3MIUevery 3 days and group two treated with diclofenac. 50 mg two times daily with heel pads. The study conducted for 12 week. Results: 92% of group one patients who received interferon alpha 2b became completely asymptomatic at week 6. At week 12 96.8% became completely free of symptoms.Conclusion: Treatment with interferon alpha 2b in patients who had plantar fasciitis seems to be effective bringing complete cure.