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Background & Aims: Considering the increasing prevalence of breast cancer, today, the main problem in the field of women's health is the control and prevention of breast cancer. One of the main areas in preventing this disease is controlling the risk factors associated with lifestyle. Wearing of brassiere is also a lifestyle-related habit that has sparked many debates today as a risk factor for breast cancer in women. This study was conducted to determine the behavioral Habits of wearing brassiere in women with and without breast cancer. Materials & Methods: This case-control study was conducted on women with and without breast cancer.A total of 360(120 in the case group -240 in the control group) individuals were selected based on available sampling method. The study tools were Demographic and behavioral habits of wearing brassiere questionnaires. Data were analyzed by Descriptive (mean and standard deviation, Frequency) and analytical tests (Independent t test and Chi-square) by using SPSS version 18 software. Results: Based on the results, the average hours of wearing brassiere in women with and without breast cancer was 19.2 ± 3. 21 and 17.9 ± 3.19 respectively. The mean frequency of wearing brassiere during sleep in women with and without breast cancer was 5.78 ± 1.16 and 4.18 ± 0.83 times per week. There was a significant difference between the two groups regarding the average hours of wearing brassiere, the mean frequency of wearing brassiere during sleep and the habit of wearing a tight brassiere (p