The observed response to [131I]MIBG therapy in advanced neuroblastoma after conventional therapy, the noninvasiveness of the procedure, and the high metabolic activity which is frequently observed in untreated tumors led to the concept of substituting [131I]MIBG therapy for combination chemotherapy at diagnosis prior to surgery in patients with advanced disease/high risk neuroblastoma. The objective of this approach is to reduce the tumor volume, enabling adequate surgical resection of the tumor, and to avoid toxicity and the induction of early drug resistance. Chemotherapy is reserved to treat minimal residual disease postoperatively. Thirty-one children who presented with inoperable neuroblastoma were treated according to this protocol. After an objective response to [131I]MIBG therapy at diagnosis, 19 of 27 evaluable patients (70%) had complete or > 95% resection of the primary tumor or did not require surgery at all. Only mild hematological toxicity was observed. It is concluded that [131I]MIBG therapy of neuroblastoma at diagnosis is feasible; its effectiveness in attaining operability of the primary tumor is at least equal to that of combination chemotherapy, but its toxicity is considerably less.