Using the Minnesota Multiphasic Personality Inventory (MMPI), the present study was conducted to compare personality traits between cigarette-user and non-cigarette-user undergraduate students studying at Zahedan University of Medical Sciences. The population, in the present descriptive-analytical study, consisted of all medical students studying at Zahedan University of Medical Sciences (386 students).The whole population was considered as a census sample and entered the study. The short form of MMPI was used for data collection. Content validity of the MMPI has been confirmed. The results indicated that, the average scores of smokers were higher than those of non-smokers in 6 clinical scales of the MMPI (Hypochondriasis (Hs), Social Introversion (Si), Paranoia (Pa), Psychasthenia (Pt), Hypomania (Ma) & Schizophrenia (Sc)) and except for the Hs scale, there were significant differences between smokers and non-smokers. Considering the two other clinical scales of the MMPI (Depression (D) & Hysteria (Hy)), the average scores of non-smokers were higher than those of smokers and the difference in the scale of Hy was significant.