7-year-old girl treated for acute lymphoblastic leukaemia since June 1995 after marrow relapse (June 1997) presented with painful oedema of the upper part of left hip and limping, 16 months after allogeneic bone marrow transplantation (BMT). Bone marrow examination excluded medullary relapse. Histopathological investigation of periosteum and bone scrapings revealed massive leukemic infiltration. Radiotherapy resulted in local arrest of the malignant process. However, bone marrow relapse was diagnosed in the child two months later with subsequent death after one month.