Chronic oral etoposide has shown activity in some metastatic refractory tumors. To test its activity in previously treated metastatic breast cancer patients, we started a study in 18 consecutive patients given etoposide orally at 50 mg/m2 daily for 21 days. A partial response was observed in 4 of 18 patients (22%); of the responding patients, 3 had visceral metastases and 1 had multiple bone metastases. Leukopenia of grade 3 or 4 was the main hematological toxic effect (23% of patients) and alopecia was the most important nonhematological toxicity. Chronic oral etoposide shows some activity in pretreated patients with metastatic breast cancer, with tolerance being good and toxicity, acceptable. Further studies of this drug given as first-line chemotherapy or in combination with other drugs can establish all its potential activity in this cancer.