Breast cancer is a malignant tumor that often attacks women in the world. Breast cancer is now the number one killer of women in Indonesia, which are 21.5 per 100,000 populations (2013). Province of Special Region of Yogyakarta is ranked first with the highest prevalence of breast cancer in Indonesia, that is equal to 2,4% or 4,325 people population. Breast Self-Examination is one way of early detection of breast cancer. The success of Breast Self-Examination is one of them influenced by behavior. Purpose of this research is to know the compare of Breast Self-Examination behavior of medical student and non-medical students in Universitas Muhammadiyah Yogyakarta. This research use descriptive comparative research design with cross-sectional approach. Technique sample use proportional random sampling with 349 respondents. The research was conducted at April of 2017, by distributing questionnaires. Data analyze use Mann-Whitney Test. The age characteristics of the respondents in both groups were dominated by 20 years old. Almost half of the respondents have good enough behavior, on medical students (82 respondents) and non-medical student (77 respondents). Mann-Whitney Test analysis results obtained p value = 0.002. Average result of Breast Self-Examination on medical student is well than non-medical student. The research conclusion is there is a difference Breast Self-Examination behavior between medical and non-medical students in UMY