High-dose chemotherapy often requires hematopoietic progenitor cell reinfusion, but drugs with extramedullary dose-limiting toxicity may be administered in the high-dose range by simple growth factor support. In this study, we evaluated the feasibility and toxicity of a three-drug high-dose regimen supported by recombinant human granulocyte colony-stimulating factor (rhG-CSF). Ten patients with histologically proven malignancy were enrolled. Eight had breast cancer, one non-Hodgkin's lymphoma, and one a mediastinal tumor of unknown origin. The regimen included cyclophosphamide (C) 5 g/m2, etoposide (E) 1.5 g/m2, and cisplatin (P) 150 mg/m2 (CEP), administered in a 3-day schedule followed by rhG-CSF, 300 micrograms once a day, beginning from day +5 (36 h after the end of chemotherapy). The cycle was repeated as clinically needed up to three times. After the first course, hematologic recovery was rapid and complete without documented infections, and no relevant extramyeloid toxicities were observed. Eight of 10 patients received a second course with comparably low toxicity, and three of them received a third course. We concluded that CEP therapy can be administered safely and even repeatedly, by simple growth factor support, in good performance status cancer patients.