Introduction:Behçet’s Disease (BD) is a systemic vasculitis, highly prevalent in Eastern Asia to Mediterranean countries. Iran is among the countries with the highest prevalence of BD, and previous studies in different countries have shown a broad range of clinical manifestations of the disease. The present study is conducted to evaluate the prevalence of the clinical manifestations of BD in patients referring to rheumatology clinics of two distinct referral hospitals in Tehran and Zanjan, Iran.Methods:In this retrospective, cross-sectional study, the medical records of patients with BD were reviewed, and age at onset, sex, the delay between the onset of symptoms and diagnosis, clinical manifestations, HLA B27, HLA B51, HLA B5, haematuria, proteinuria, leukocyturia, Erythrocyte Sedimentation Rate (ESR), and pathergy phenomenon were included in the study. The collected data were analysed by χ2test using SPSS 23.Results:A total of 188 patients (Male/female ratio = 1.47) were included in the study with mean ± SD age at onset of 27.98 ± 10.47 years and a mean ± SD of delay between the onset of symptom and diagnosis of 5.70 ± 7.16 years. The most common clinical manifestation was mucosal involvement (85.1%), followed by the ocular lesion (55.3%) and skin manifestations (44.7%). The Pathergy phenomenon was observed in 98 patients (52.1%). Moreover, 45.2% had positive HLA B5, followed by HLA B51 (35.1%) and HLA B27 (12.2%).Conclusion:This study demonstrated that male/female ratio and mean age at onset were comparable to the results of previous studies in Iran. Significant associations between HLAB5 and clinical manifestations underline the pivotal role of genetic factors in BD.