The aim of our study was to evaluate the impact on time to progression (TTP) and overall survival (OS) of high-dose chemotherapy (HD-CT) over conventional CT in metastatic breast cancer patients. Between 09/92 and 12/96, 61 patients with chemosensitive metastatic breast cancer were randomised between HD-CT using the CMA regimen (Mitoxantrone, Cyclophosphamide, Melphalan) applied as consolidation (32 patients) or maintenance CT (29 patients). At randomisation, 13 patients were in complete response, 47 in partial response and one had stable disease. The median TTPs from randomisation were 6 and 12 months in the standard and intensive groups, respectively (P < 0.0056), with a relapse rate of 86.2% vs. 62.5% at 2 years, and 100% vs. 81.3% at 5 years. The median OS times were 19.3 and 44.1 months, with an OS rate of 13.8% vs. 36.8% at 5 years (P < 0.0294). The CMA regimen could prolong the TTP of patients with chemosensitive metastatic breast cancer. Further studies are needed to determine if this translates into an effect on OS.