The expected median progression free survival of metastatic breast cancer patients who achieve a disease control after first line chemotherapy was estimated to be 10 months. The minimal improvement, justifying the adoption of maintenance paclitaxel, was estimated to be at least 3 months. With 262 eligible patients on each arm, the trial will have a power of 80% to detect a 30% improvement in median progression free survival, testing at the two-sided .05 significance level.