Purpose: The purpose of this study was to investigate the perceived sources of stress among dental students. The relationships of these stresses to the year of study and gender were also examined. Methods: The responses from the first to fourth year dental students to 30 items adapted from Dental Environment Stress (DES) questionnaire were subjected to confirmatory factor analysis. The Likert scale, ranging from 0 (not applicable) to 4 (very stressful), was applied to these items. A total of 341 students (male=196, female=145) participated, their average age being 24.7. Multivariate analysis of variance (MANOVA) was conducted to analyze the effects of the year of study and gender on stressors. Results: Confirmatory factor analysis established a five-factor model including 1) clinical practice, 2) academic load and pressure, 3) personal problems, 4) low self-esteem, and 5) school administration or climate. Subscales for each factor show good internal consistency with Cronbach s alpha ranging from .71 to .88. Mean score for factor II (academic load and pressure) was the highest among all factors for all of 4 years, which meant that primary stressors were amount of classwork, shortage of time, and competition among classmates regardless of the year of study. MANOVA result showed that the amount of stress from clinical practice and school climate generally increased through the years (p＜.01), and that female students were more stressed than male students (p＜.01). Conclusion: Students stress is related to the features of the curricula and the learning environment. In reducing this stress, it would be helpful to modify the curriculum as well as to introduce mentor or counselor programs.