Abstract: Introduction: The latest nationwide survey on Behcet’s disease (BD) in Iran was carried out in 2001. We present here its data, and compare it with the previous two surveys in 1991 (on 1882 patients) and 1996 (on 3153 patients). Patients & methods: The data of patients in the BD registry before the end of the year 2001 were collected on a standard protocol comprising 100 clinical and paraclinical items. A confidence interval (CI) at 95% was calculated for each item. The comparisons were made by chi square test. Results: A total number of 4704 patients were analyzed. The annual incidence rate was 280 patients for a population of 65 millions in the last 5 years; lower than 345 in the 1996 survey. The male/female ratio (1.14) and the mean age (269.7, CI:0.3) showed no significant changes. Among the first manifestations, oral aphthosis was seen more frequently (80%, CI:1.1), while uveitis (10%, CI:0.8) and joint involvement (5%, CI:0.6) were less encountered. The prevalence of skin (70%, CI:1.3), notably pseudofolliculitis (62%, CI:1.4) and ocular (56%, CI:1.4) lesions (both uveitis and retinitis) was lower. The same decrease was seen for the deep vein thrombosis (6%, CI:0.7), joint (35%, CI:1.4) and GI involvement (8%, CI:0.8), and the positivity rate of the pathergy test (58%, CI:1.4). No significant changes were found in the other manifestations of the disease. Conclusion: Recent nationwide survey in Iran revealed a remarkable decrease of the incidence rate of BD and a tendency toward milder forms of the disease.