Between January 1993 and December 1996, 21 children with advanced solid tumors were entered in a dose-escalating study of high-dose sequential chemotherapy followed by autologous stem cell transplantation. The diagnoses included neuroblastoma (NB) for 13 patients; Ewing's sarcoma (ES) for six patients and osteosarcoma for two patients. Nine patients received therapy as consolidation for primary metastatic disease, and 12 patients had had previous relapses. Treatment consisted of CY given i.v. at a dose of 7 g/m2 on day 1, followed by G-CSF until myeloid recovery. After 3 weeks of rest, all patients were given thiotepa i.v. on days 22-24. The total dose of thiotepa was 450 mg/m2 in three patients, 600 mg/m2 in six patients, and 750 mg/m2 in 12 patients. Melphalan was given i.v. at a dose of 180 mg/m2 i.v. on day 27 followed by stem cell infusion on day 28. Major toxic reactions included stomatitis, esophagitis, diarrhea and dermatitis. Three patients died of treatment-related complications. Twelve patients have had a relapse. Six patients (five with NB and one with ES) are alive in continuous remission 5-50 months (median 36) after transplantation. The results of this study show that it is feasible to administer high-dose sequential chemotherapy to children with advanced solid tumors.