Infantile fibrosarcoma, an uncommon disease of childhood, generally occurs in an extremity and despite high local recurrence rates is usually curable with surgical excision alone. Two patients whose tumors were unresectable because of extensive retroperitoneal involvement are reported. Treatment with doxorubicin, vincristine, and cyclophosphamide resulted in complete clinical responses in both patients. They remain alive and tumor free 2.5 and 4 years from diagnosis. Chemotherapy as a single modality appears to be effective in controlling unresectable infantile fibrosarcoma.