Abstract: Brain Drain is the departure of educated or professional people from one country, economic sector, or field for another usually for better pay or living conditions[1] Objectives: To know the determinants of brain drain among medical students Design: Case control study Place: King Edward Medical University Study period: 3 months Subjects and Methods: Case-control study with 1:1 case to control ratio was conducted. A total of 300 subjects [150 cases and 150 controls] were recruited in study. 147 males [49%] and 153 females [51%] were part of the study. Informed consent was taking from the participants. Convenient sampling was used. Data was collected, compiled and analyzed by using SPSS version 16. After describing the demographic characteristics using frequency tables, simple and multivariate logistic regression were used to calculate odds ratio and their 95% confidence intervals. Results: Better quality of training [OR: 12.642 95% CI: 7.306-21.873] and following footsteps of elder sibling [OR: 6.00 95% CI: 1.720-20.933] are the two main determinants of our study. Other factors included better social life abroad, better career opportunities, favoritism in our country and better pay package, better living conditions, lack of research opportunities in this setup, relatives residing abroad, fewer promotion opportunities in Pakistan, better PG training, flexible working hours in foreign countries and security issue in our country were also significant. Keywords: Brain Drain, Physician Migration, Health sector, Emigration.