This study aimed at comparing mental health among students who are studying in different fields of study in Islamic Azad University (IAU) Karaj Branch. In this descriptive research which was a causal-comparative type of study, 330 students were randomly selected out of eleven faculties in IAU Karaj branch. The General Health Questionnaire (GHQ) (1997) was administered to measure the mental health of the students. The results of MANOVA and Tukey follow-up test analysis indicated that there was a significant difference in total scales and all subscales of general health among students in all eleven faculties.