Resumo BACKGROUND: The purpose of this study was to identify whether psychological stress increased as undergraduate dental students progressed through their studies from first to fifth year. Another objective was to determine if the perceived sources of stress have changed along the years. METHODS: To achieve these aims, a cohort of students at the University of Jordan were followed from first to fifth year of dental school. Fifth year students completed both the General Health Questionnaire 'GHQ-12' which was used to assess psychological stress and the Dental Environment Stress questionnaire 'DES' which was used to examine the perceived sources of stress. The same cohort of students had completed similar questionnaires during their first year of study. Chi-square analysis and independent t-test analysis were performed to compare GHQ-12 and DES scores between first and fifth year. RESULTS: Results showed that psychological stress increased from first to fifth year of study. Eighty- nine percent of fifth year students scored over the cut-off point of three in the GHQ-12 compared to 58 % in the first year. The difference between the years was statistically significant at p = 0.05. Mean score for DES also increased between first and fifth year of study and the difference was statistically significant at p = 0.05. CONCLUSIONS: Results of this study demonstrated that stress in dental students at the University of Jordan increased along the years. Fifth year students showed a high level of psychological stress and methods to reduce that stress should be further investigated and utilized.