We analysed the 2-year event-free survival (EFS) of 49 patients 1 year of age and older, with stage 2B or 3 neuroblastoma, treated on Pediatric Oncology Group protocols 8742 and 9244, with respect to the degree of tumour resection at diagnosis. The 2-year EFS rate for 21 children whose tumours were completely resected at diagnosis was 85% (SE = 10%) compared with an EFS rate of 70% (SE = 9%) for the 28 children whose tumours were incompletely resected at diagnosis. Despite the observed trend in favour of complete resection, these EFS curves were not statistically significantly different (P = 0.259). Patients with favourable Shimada histology tumours had an EFS rate of 92% (SE = 7%) compared with a rate of 58% (SE = 15%) for patients with unfavourable histology tumours. EFS curves for the two histologic groups were significantly different (P = 0.009). The impact of aggressive surgery and adjuvant chemotherapy on the outcome of patients with biologically favourable regional neuroblastoma is still unclear.