Purpose The aim of this study was to investigate the effect of a peer education program on nursing students' beliefs toward mental illnesses and their career choices.,Design and Methods This one-group quasi-experimental study was conducted with 95 undergraduate nursing students.,Findings The peer education program positively affected nursing students' beliefs toward mental illnesses (p < 0.005). It was determined that the students preferred psychiatric nursing more as a career field after the peer education program.,Practice Implications Peer education programs may be a part of the nursing curriculum in combating stigma toward mental illnesses.