An 11 year-old boy was treated for acute promyelocytic leukemia (ALM3) with chemotherapy according to the LAME 86 protocol (aracytin and rubidomycin). The first complete remission was consolidated by two autologous bone marrow transplantations. Following autologous graft, a persistent thrombocytopenic purpura appeared. Autoimmune origin was indicated by a decrease in platelet survival time and by the presence of high levels of antiplatelet antibodies.