Background: The natural history of ocular lesions in Behçet's disease is toward severe loss of vision/blindness in few years, whereas cytotoxic drugs have changed the outcome. Several open labeled cohort studies showed pulse cyclophosphamide (PCP) to be the best choice. Since one third of these patients are resistant to PCP it is important to know how much improvement one can expect from the responders. To address this question, we selected patients who improved or maintained their baseline visual acuity after treatment. Methods: From a cohort of 528 patients (1056 eyes), 753 eyes were selected. At the beginning of the study PCP was given for one month as 0.75 to 1 g in perfusion, and then followed every 2 to 3 months. Prednisolone was also given as 0.5 mg/kg/daily and then tapered upon controlling inflammation. The mean±SD number of pulses was 11.5±8.5/month with follow-up of 20.6±19.8 months. Different disease activity indices such as visual acuity, posterior uveitis, retinal vasculitis, total inflammatory activity index (TIAI), total adjusted disease activity index (TADAI) were calculated at baseline and at last evaluation. Results: The mean visual acuity improved from 2.4 to 4.4. The mean indices for posterior uveitis, retinal vasculitis, TIAI and TADAI improved from 2.2 to 1, 2.7 to 1.4, 19.3 to 9, and 27.2 to 20.5 respectively. The P value was less than 0.001 for all comparisons. Conclusion: Pulse cyclophosphamide is able to improve ocular lesions of Behçet's disease; therefore it may be used as a first choice, especially in retinal vasculitis.