Objective:The aim of the study was to evaluate the ef icacy and tolerability of single-agent gemcitabine in the maintenance treatment of histological y confirmed metastatic breast cancer cases. Methods:The 45 patients carried ef-ficacious chemotherapy were divided into maintenance therapy group (n=23) and control group (n=22) according to the dif erent treatment methods. Patients in the maintenance therapy group received gemcitabine therapy until 6 cycles, disease progression or adverse ef ect intolerance. Within the control group, the patients were given best supportive care. Fol ow-up was made until disease progression, death or 2 years. The short-term clinical ef icacy and adverse ef ects, progression-free survival (PFS) and median survival of recurrence (MSR) of these two groups were compared and analyzed. Results:Com-pared with the control group, the experiment group had higher response rate (RR;73.9%vs 31.8%;P