The aim of this study was to identify dental students' self-reported sources of stress and to explore the role of specific curricular and institutional differences in the variation of perceived stressors among dental students in Greece, Ireland, Slovenia, Sweden, Spain, and Croatia. A thirty-item modified version of the Dental Environment Stress (DES) questionnaire was administered to all undergraduate students enrolled at six European dental schools selected to reflect geographical, curricular, and professional environment diversity: Athens, Greece; Dublin, Ireland; Ljubljana, Slovenia; Malmö, Sweden; Santiago de Compostela, Spain; and Zagreb, Croatia. Participation varied from 93 percent in Athens to 65 percent in Dublin. A total of 1,492 questionnaires were available for analysis. Univariate analysis and multivariate modelling were used for data analysis. Performance pressure, workload, and self-efficacy beliefs constituted the students' main concerns. In the univariate analysis, student responses differed by country: Swedish students provided the lowestst scores in five out of six DES factors, Spanish students were the most concerned about "clinical training" and "performance pressure," whereas Greek students were the most concerned about "patient treatment." Multivariate modelling revealed that problem-based learning (PBL) was inversely associated with perceived stress for "self-efficacy beliefs" OR (95% CI): 0.66 (0.52, 0.84), "workload" OR (95% CI): 0.58 (0.41, 0.80); and "clinical training" OR (95% CI): 0.69 (0.50, 0.95) when compared to traditional curricula. Students' perceived stressors differed greatly among the six institutions and were associated with both individual (gender, study level) and educational/institutional (curriculum type, class size, educational costs) parameters.