Pyoderma gangrenosum is a neutrophilic dermatosis that is frequently associated with malignancies such as myeloproliferative disorders. The development of this dermatologic disorder is thought to be mediated by immunological mechanisms. A case of pyoderma gangrenosum associated with the administration of alpha2b-interferon (alpha2b-IFN) in a patient with chronic granulocytic leukemia is described. Discontinuation of alpha2b-IFN and the administration of cyclosporin A and prednisone resulted in cure of the pyoderma gangrenosum. Serum levels of tumor necrosis factor, interleukin-6 and soluble interleukin-2 receptor increased when the cutaneous lesions appeared and returned to normal levels when the lesion healed. We believe that this is the first reported case of pyoderma gangrenosum associated with alpha2b-IFN therapy.