Capecitabine, a tumor-selective, oral fluoropyrimidine, has demonstrated significant antitumor activity in patients with metastatic breast cancer. In this open-label monocenter phase II study the efficacy and safety of capecitabine in patients with metastatic breast cancer who relapsed after high-dose chemotherapy was examined. Female patients 18-65 years of age, with a histologically confirmed diagnosis of metastatic breast cancer, who relapsed after high-dose chemotherapy (adjuvant and/or metastatic) followed by autologous peripheral blood stem cell transplantation (PBSCT) and who had been treated in their course of the disease with an anthracycline and/or an anthracycline/taxane containing regimen were included into this clinical study. Capecitabine was applied as the first salvage chemotherapy at relapse after high-dose chemotherapy (1250 mg/m2b.i.d. p.o. for 14 days followed by 7 days rest period). Responding patients or those with stable disease after two treatment cycles were offered to continue treatment until tumor progression. Response rate, time to disease progression, survival, toxicity and quality of life were assessed. Fourteen patients between 35 and 60 years (median 45.5 years) entered this study and received a median number of 5 cycles (range 1–19) of capecitabine. All patients were evaluable for response. All patients had been pretreated with 1–2 cycles of high-dose chemotherapy plus PBSCT. Furthermore, 13 patients had additionally received local radiotherapy. On average, the patients showed metastatic disease in two organ sites (range 1–4 sites). One patient obtained a complete response and five patients a partial response, accounting for a response rate of 42.9% [95% confidence interval (17.7%; 71.1%)]. All responses were already achieved at the first observation time point 6 weeks after treatment initiation. Two further patients obtained stable disease for at least 12 weeks. At the time of final analysis all patients have progressed. Median time to progression was 2.8 months (range 0.4–13.3 months). No median survival time was reached (range 3.9–36.5 months, at the time of reporting eight patients were alive and six patients had died). Two patients developed grade III granulocytopenia. Five patients developed grade III hand–foot syndrome. One patient had the combination of nausea, fever and diarrhea grade III. All adverse events were considered manageable. We conclude that capecitabine as single-agent oral chemotherapy is active and well tolerated in heavily pretreated patients with breast cancer. It can be safely used in patients who have been intensively pretreated by myelotoxic chemotherapy or who have even relapsed after high-dose chemotherapy with PBSCT.