Abstract: Objective To analyze the major causes of breast cancer drug clinical trials’ patients expulsion and find new methods to reduce the expulsion rate. Methods The report collected the messages of patients who participated the breast cancer drug trial in my hospital from June 2012 to January 2015 and analyzed the patient’s expulsion reasons. Results Among the 405 subjects, the expulsion of 85 participants were recorded. The major causes of patient expulsion were patients’ compliance and psychological features. The patients who had less compliance had a higher expulsion rate than those who had better compliance[70.9%（44/62） vs. 11.9%（41/343）] and the difference was significant（P<0.01）. The expulsion rate was more significant in the patients who had obvious psychological features[57.1%（20/35） vs. 17.6%（65/370）] with significant difference（P<0.01）. The distributions of drug types， medication， the courtyard frequency and clinical trial stage between the compliance and fall off patients had no significant difference. Conclusion To reduce the patient expulsion rate of breast cancer drug trials， we can focus on the management of patients and physicians and solve the adverse events in time.