Objective: To investigate women patients' knowledge of breast cancer in a hospital in Macau. Method: A convenience sample of 179 women were chosen at departments of obstetrics and gynecology and data collected using a structured questionnaire. Result: the ratio of answering correctly the questions on knowledge of breast cancer was less than 50%, amongst whom, only 37% knew well of the early symptoms and 23% of the risk factors Their knowledge of breast cancer screening varied according to the differences in marriage status, career, family income, and whether people around had ever had breast cancer. Conclusion: The women patients had low cognition of breast cancer. It is suggested that the government and medical organisations should strengthen the education on breast diseases.