Objective: We aimed to evaluate the clinical spectrum of Behçet's disease in both pediatric and adult patients, and find out the risk factors for severe organ involvements. Material and methods: Results of 595 patients diagnosed with Behcet's disease according to International Behcet's Disease Study Group (1990) criterias, admitted to the dermatology department, Behcet's disease polyclinic of Haseki Training and Research Hospital between 1993-2016 years were evaluated. Results: A total of 595 patients with Behçet's disease (305 male, 290 female, 17 children) with a mean age of 32,9±9,4 years (between 12 and 65 years) were enrolled. The prevalence of mucocutaneous lesions and system involvements was as follows: oral aphthae 100 %, genital ulcer 83,5% , papulopustular lesions 56,8 %, erythema nodosum 37,5 %, pathergy positivity 45,2%, articular involvement 67,7%, eye involvement18,9 %, vascular involvement 6,7%, neurologic involvement 1,5% and gastrointestinal system involvement 0,2 %. While papulopustular lesions, pathergy positivity and vascular involvement were found more frequently in males, eritema nodosum was more common in females. Neurological involvement was significantly more frequent in patients with ocular involvement (p=0,014). Genital ulcer, skin findings , articular and ocular involvement were detected less frequent in patients with positive pathergy reaction. Clinical features of children were similar to the adults. Conclusion: Ocular involvement in Behçet's patients may be a predictor for other serious organ involvements. While pathergy positivity was evaluated as a good prognostic factor, male gender was associated with a poor prognosis.