OBJECTIVES: The purpose of this study was to investigate the job stress level of post-graduate students in schools of natural sciences and engineering in order to evaluate the relationship between temperament, character and job stress. METHODS: All the 254 subjects were interviewed by means of a structured questionnaire, KOSS-SF and TCI-RS. Among them, only 220 were eligible for analysis. Statistical methods used included chi-square test, independent t-test, Mann Whitney test, ANOVA test, correlation analysis and multiple linear regression analysis with PASW ver.18. RESULTS: Age, degree course, working hours per week, work tenure, smoking habits, exercise, and disease history were associated with job stress and hours worked per week, smoking being associated with TCI-RS subscales. For job demand, interpersonal conflict scores were higher than Korean standard. In multiple linear regression analyses, R2 scores of temperament subscales on job stress were 0.099~0.312 and those of character subscales on job stress were 0.056~0.249. CONCLUSIONS: Job stress was associated with the unique traits of individuals, temperament and character. In order to manage job stress, the personality, as well as work environment, was found to be important considerations.