A 75-year-old man presented with painful oral and groin ulcers. The lack of any infections and the location of the ulcers suggested Behçet's disease. Subsequently, pancytopenia developed and bone marrow examination revealed myelodysplastic syndrome. Cytogenetic examination revealed 7q- and 20q- but not 8+. Immunosuppressive therapy with cyclosporine and corticosteroid resulted in a dramatic improvement in both clinical signs and hematologic abnormalities.