Background : Altruism is one of the attribute of doctor’s professional behavior. Social norm determines how human behave. Thus, this has to be anticipated. The aim of this study is to find the association between social norm and altruism on Medical Students of Universitas Muhammadiyah Yogyakarta. Method : This is a descriptive-analytic, cross sectional study. This study was conducted at Medicine Faculty of Universitas Muhammadiyah Yogyakarta from August to December. There were 273 Medical students of Universitas Muhammadiyah Yogyakarta involved as respondents. 117 (42,9%) were male, and 156 (57,1%) were female. The data were analysed with product moment test from Pearson. Result : Statistical analization revealed p = 0,591, which shows that social norm has a medium-category positive association with altruism. The degree of social norm on the respondents of this study were low (12,1%), medium (65,9%), and high (22%), while the degree of altruism on Medical Students of Universitas Muhammadiyah Yogyakarta on this study were low (22,3%), medium (60,4%), and high (17,2%). Conclusion : There was association between social norm and altruism on Medical Students of Universitas Muhammadiyah Yogyakarta.