SUMMARY: We present a unique case of a bone marrow stem cell transplanted (BMT) patient with cutaneous chronic Graft versus Host Disease (cGvHD) who underwent successful allogeneic split-thickness skin graft (STSG) transplantation. BMT had previously been carried out due to myelodysplasia and non-Hodgkin's lymphoma of the patient. Pre-BMT human leucocyte antigen (HLA)-typing had revealed identity between the donor and the recipient, who were siblings (not twins). Complete donor chimaerism was achieved. The recipient developed severe cGvHD with ichthyosis-like dryness and scleroderma. A folliculitis evolved to a full thickness ulceration on the entire scalp. From the femoral region of the donating sister a STSG was harvested under local analgesia and transplanted without analgesia to the prepared scalp ulcer of the recipient. The result was full and permanent take of the allogeneic STSG (follow up: three years). Allogeneic skin grafts are known to be acutely rejected. Successful allogeneic STSG has only been reported in sporadic cases of identical twins (isotransplantation). This case is the first to demonstrate what works in theory: the immune system of a stem cell transplanted patient with 100% or mixed stable donor chimaerism will not recognise skin from the stem cell donor as foreign. Due to advances in haematology, the number of BMT patients and their long-term survival is expected to increase. cGvHD, predisposing to skin problems and ulcerations, complicates up to 70% of cases of BMT. In BMT patients with cGvHD and large skin defects, allogeneic STSC from the BMT donor seems to be a safe alternative for permanent coverage.