BACKGROUND AND DESIGN: Pyoderma gangrenosum is a chronic inflammatory ulcerative skin disease of unknown origin, often associated with various diseases including inflammatory bowel disease, inflammatory arthritis, monoclonal gammopathies, hepatitis, and myeloproliferative disorders. Treatment of associated systemic disorders may improve the ulcers, but lesions may be recalcitrant and persist for months to years. Therapy for pyoderma gangrenosum includes high-dose systemic corticosteroids, sulfa drugs such as sulfasalazine, clofazimine, and immunosuppressive agents such as mercaptopurine and azathioprine; these drugs are sometimes ineffective. RESULTS: We present a series of 11 patients with pyoderma gangrenosum, with a wide range of underlying diseases, whose ulcers were refractory to usual therapy and who were treated with low-dose cyclosporine. Ten of the 11 patients cleared rapidly and completely with cyclosporine therapy. CONCLUSIONS: Cyclosporine should be seriously considered as a primary form of treatment for pyoderma gangrenosum.