This study reports a large cooperative experience in myeloablative therapy and bone marrow rescue undertaken to define better the outcome of children with disseminated neuroblastoma after megatherapy. Between 1984 and 1993, 135 children underwent myeloablative therapy with bone marrow transplantation (BMT) in nine Italian Centres. One hundred and seventeen children received unpurged autologous BMT, five allogeneic BMT and 13 peripheral blood progenitor cells as rescue. Of these 135 children, 57 were in 1st CR, 11 in 2nd or subsequent CR, 42 in 1st PR, and 25 had more advanced disease. Twelve children (9%) died of toxicity, 86 relapsed or progressed at 1-68 months (median 7 months) and 80 of these subsequently died of progressive disease. Forty-three children are still alive with 37 in continuous remission at a median of 65 months (30-123 months) after BMT. Overall and disease-free survival at 8 years are 28.5% (s.e. 4.3) and 26% (s.e. 4), respectively. Disease-free survival is 34.6% (s.e. 6.7) for the patients grafted in 1st complete remission, 23.6% (s.e. 6.6) for patients grafted in 1st partial remission, 36.4% (s.e. 14.5) for patients grafted in 2nd or subsequent CR, and 8% (5.4) for patients with advanced disease. We conclude these data confirm that early toxicity of myeloablative therapy is manageable and that myeloablative therapy with bone marrow rescue may contribute to an improved long-term survival of children with disseminated neuroblastoma but the objective of cure of all patients remains distant.