We report a case of rapidly-progressive glomerulonephritis complicating Behcet's disease (BD). A 44-year-old male has suffered from recurrent oral ulcers and retinal vasculitis developed 2 years ago. He complained of abdominal pain and papulopustular skin lesions. Multiple ulcers were seen on the colon on colonoscopy. Routine renal work-up revealed heavy proteinuria and hematuria. Renal biopsy demonstrated crescentic glomerulonephritis. Most symptoms improved after steroid therapy, except for urinary abnormalities. At this point, intravenous monthly cyclophosphamide pulse therapy was undergone. After the sixth pulse therapy, proteinuria and hematuria were dramatically improved and renal function was well preserved.