PURPOSE Fifty-nine patients with newly diagnosed metastatic breast cancer were treated with induction chemotherapy followed by high-dose intensification and autologous stem-cell rescue (ASCR) to determine therapeutic efficacy. PATIENTS AND METHODS Induction consisted of cyclophosphamide, doxorubicin, vincristine, and methotrexate with leucovorin rescue (LOMAC) in 27 patients, or fluorouracil, cisplatin, doxorubicin, and cyclophosphamide (FCAP) in 32 patients. Intensification after LOMAC was cyclophosphamide and thiotepa (CyTepa) with ASCR, and after FCAP it was cyclophosphamide, thiotepa, and carmustine (BCNU) in all but eight patients who received CyTepa. RESULTS Median survival from study entry for the entire group was 13.3 months. Median time to progression from reinfusion for the 45 patients who underwent intensification was 7.5 months. After LOMAC and intensification, there were 12 complete responses (CR) (nine partial responses [PRs] after induction converted to CRs). Responses after FCAP and intensification were eight CRs (two PRs after induction converted to CRs). Median time to treatment failure from reinfusion was 5.4 months for LOMAC and intensification, and was 10.5 months for FCAP and intensification. Median survival from study entry was 15.1 months for all 27 LOMAC patients and 9.3 months for all 32 FCAP patients. Median time to treatment failure from reinfusion for 11 patients who were CRs at intensification has not been reached and is more than 13 months compared with a median of 5.5 months for the 23 patients in partial remission at intensification. CONCLUSIONS High-dose intensification therapy has led to increased CR rates in metastatic breast cancer. The role of such therapy in the treatment of stage IV breast cancer requires further refinement.