Based on previous work demonstrating the activity of cyclophosphamide and melphalan in a series of human medulloblastoma and rhabdomyosarcoma cell lines and transplantable xenografts, investigations were conducted to define the effects of combining cyclophosphamide or melphalan with VP-16. These studies demonstrated a synergistic interaction between cyclophosphamide and VP-16 and melphalan and VP-16 in the treatment of the human rhabdomyosarcoma cell line TE-671 growing in athymic mice. The combination of cyclophosphamide or melphalan with VP-16 may warrant consideration as a therapeutic strategy for solid tumors sensitive to bifunctional alkylating agents.