Introduction: The purpose of this research is to compare personality traits and mental health in athletes and nonathletes students. Method: 67 athletes and 64 nonathletes students were randomly selected and NEO-PIR inventory and General Health Questionnaire (GHQ)were administered on them. Data were analyzed with independent T formula. Results: Findings showed significant differences between variables. Nonathletes have more neuroticism personality trait and were high in components of mental illness. Discussion: It is concluded sport rehearsals and physical fitness have positive effects on temperament and mood and reduce mental illness symptoms and give sense of happiness and newness in life.