A case of porphyria cutanea tarda (PCT) occurring after bone marrow transplantation (BMT) is reported. A 43-year-old male with chronic myelogenous leukemia received an human leukocyte antigen (HLA)-identical allogeneic transplantation with T-cell depleted marrow. Because of graft rejection, a second transplant was performed 4 months later. A grade II acute graft- vs.-host disease and a cytomegalovirus (CMV) infection were subsequently observed. Two years after the second transplant, cutaneous symptoms of PCT with typical biochemical abnormalities developed. Liver biopsy revealed signs of hepatitis with iron overload. CMV was isolated from liver tissue. The possible roles of underlying disease, BMT, and CMV liver disease are discussed in view of the recently reported cases of PCT in patients with AIDS or hematological disorders.