PURPOSE OF REVIEW: Controversy has surrounded the use of high-dose chemotherapy for breast cancer for more than a decade. Numerous randomized trials have compared high-dose chemotherapy with standard-dose chemotherapy in metastatic breast cancer and high-risk primary breast cancer, defined by extensive axillary node involvement or inflammatory disease. The authors review the main research results of high-dose chemotherapy for breast cancer in 2002 to 2003. RECENT FINDINGS: Preliminary analyses of three randomized trials in metastatic breast cancer and seven in high-risk primary breast cancer have been reported during this period. An advantage in event-free survival has been observed in all three studies in metastatic disease and in four of the high-risk primary cancer trials, albeit with no impact on overall survival at short follow-up. These early results are consistent with the most recent Cochrane reviews, which included trials reported through mid 2002. SUMMARY: An early event-free survival advantage is apparent in favor of high-dose chemotherapy in both high-risk primary and metastatic breast cancer. Longer follow-up of those and most other trials is required to detect translation of the event-free survival differences into benefits in overall survival. High-dose chemotherapy remains a valid research strategy in event-free survival and high-risk primary breast cancer.