Behcet's disease (BD) is a multisystemic inflammatory disorder known as having a histopathological findings of vasculitis. The influence of sexual difference on BD is a well-known fact and there are several reports suggesting a more severe course of the disease among young males. The purpose of our study was to determine the effects of gender on the severity and clinical features of BD patients in Korea. The study included 1,901 patients with BD who fulfilled the criteria of International Study Group for Behcet's Disease or corresponded to the complete or incomplete type for the revised criteria of Behcet's Disease Research Committee of Japan. BD in Korea showed a female predominance (M:F=0.61:1). The skin lesions were observed in 79.9% of patients, of which 77.6% had erythema nodosum-like lesion, which was more frequent in females. The ocular lesions were more common in males showing a higher frequency of uveitis. Ocular and vascular symptoms as clinical features with severe complications or mortality were more frequent in males than in females. The mean age at the onset of patients with the worst prognosis such as ocular, gastrointestinal, neurologic, and vascular involvements was significantly younger in male than in female patients (p<0.05). In conclusion, this study elucidated the influences of sexual difference on BD in Korea.