Behçet's disease (BD) is a multisystemic vasculitis. Here we report a case of association with BD and Henoch-Schönlein purpura (HSP). He was diagnosed as having BD with oral ulcer, genital ulcer, papular skin lesion, deep vein thrombosis (DVT) and positive pathergy reaction. Ascending venograms of both legs showed segmental occlusion from both superficial femoral vein (SFV) to inferior vena cava (IVC) with intravascular thrombus. He developed abdominal pain, bloody diarrhea, microscopic hematuria, and widespread palpable purpura on both legs, compatible with HSP. Histologic examination of the skin lesion confirmed cutaneous leukocytoclastic vasculitis with IgA-containing immune deposits. The HSP-like manifestations markedly improved with high-dose steroid therapy.