We evaluated the long-term side-effects of allogeneic BMT performed early in the course of childhood acute leukaemia (first complete remission and interval between diagnosis and BMT not exceeding 6 months). Thirteen patients fulfilled these criteria. Conditioning regimens included TBI in eight cases. Evaluation of growth and pubertal development, ophthalmological examination, assessment of thyroid, cardiac and pulmonary functions were performed. Neuropsychological evaluation included IQ score, memory tests and cranial MRI. Median follow-up after BMT was 5 years (range 2-10 years). Growth was normal in seven patients. Six patients experienced a decrease in SD score for height (range -0.1 to -1.9). Four children were evaluable for puberty: pubertal development was normal in three children and delayed in one case. Thyroid and left ventricular function were normal in all cases. Three patients had mild abnormalities of pulmonary function. In two patients cataracts were noted 7 and 10 years after fTBI. Mean full-scale IQ score was 102. Memory tests, performed in 12 cases, were in the normal range for 11 patients. In our study, frequency and severity of long-term side-effects following BMT for leukemia appeared lower than usually reported. A possible explanation is that children were transplanted very early in the course of their disease with neither cranial irradiation nor long exposure to chemotherapy prior to transplant.