Ten patients with Behçet's disease were treated with chlorambucil alone. At the therapeutic drug level of 0.2 mg/kg, seven patients developed oligospermia and three patients developed azoospermia. A 30-year-old patient underwent a testicular biopsy two years after the cessation of therapy. Histopathology revealed evidence of testicular atrophy. Fifteen (75%) out of 20 eyes had a visual acuity of 20/200 or less following therapy. It is concluded that chlorambucil should not be used as the first line of therapy in Behçet's disease and that its long term benefits in patients with Behçet's disease should be reevaluated.