Abstract The origin (recipient/donor) of the myofibroblasts mediating fibrosis in sclerodermatous chronic graft-versus-host disease (cGvHD) was investigated. Sclerodermatous specimens obtained from a patient with extensive cGvHD after an HLA-identical sibling bone marrow transplantation were cultured in order to derive tissue myofibroblasts. All proliferating a-SMA+ fibroblastoid cells revealed recipient origin as examined by variable number tandem repeat (VNTR)-PCR. This case report shows that fibrosis in sclerodermatous lesions results from the activation and proliferation of locally-derived recipient fibroblasts rather than from donor-derived fibroblasts or circulating fibrocytes.