The immunosuppressive drugs are widely used in systemic involvements of Behçet's disease. This study is aimed to investigate the extent of clinical involvement and preferred treatment approaches for type of involvements in Behçet's patients from the whole country. All patients with the diagnosis of Behçet's disease were enrolled to the study. These patients analyzed whether they fulfill the International Study Group Criteria, and only those were further evaluated. Demographic and clinical characteristics, laboratory results and treatments ever used were recorded. Further analysis is done regarding clinical manifestations and preferred therapeutic approaches. A total of 863 patients with the diagnosis of Behçet's disease were detected, but 682 of them (female/male: 113/569) found to be appropriate for analysis. The remaining patients were included to the analysis. The frequencies of articular, ophthalmic and vascular involvement were 49, 43 and 21 %, respectively. Colchicine and corticosteroids were the most preferred agents. The immunosuppressive agents frequently used for organ involvements were azathioprine, cyclosporine A, interferon-α, sulphasalazine and cyclophosphamide with decreasing order of frequency. In this relatively young population composed from all over the country, the frequency of ophthalmologic, venous and neurological involvement is less frequent than previous reported cohorts. Azathioprine and cyclosporine were the drugs of choice as a chronic immunosuppressive agent in patients with organ involvement. The previously reported increased frequencies in other cohorts could be a result of the reference of severe patients to dedicated centers.