The efficacy and toxicity of a high-dose multiagent consolidation regimen, OMEC (vincristine, melphalan, etoposide and carboplatin), with autologous bone marrow rescue was studied in patients with poor-prognosis neuroblastoma, 20 patients were treated with OMEC, 18 after induction chemotherapy and 2 following relapse. All patients received, per m2, vincristine 4 mg, etoposide 1 g, carboplatin 1.0-1.75 g and melphalan 180 mg followed by bone marrow rescue. 4 patients (20%) died of treatment-related complications. Severe gastrointestinal toxicity occurred in all of these patients, and in 75% of patients overall. 1 of 5 patients with evaluable disease achieved complete remission. 13 patients (65%) have relapsed a median of 10 months (range 3-26) after receiving OMEC. Thus, OMEC was not more effective, yet more toxic, than high-dose melphalan given alone, and the use of similar multiagent regimens with overlapping toxicities in advanced neuroblastoma appears inadvisable.