BACKGROUND Stress-induced health disorders are related to an unhealthy lifestyle. This study aimed to investigate the prevalence of perceived stress among medical students and to correlate their respective stress levels with the caries index: decayed, missing, filled surfaces (DMFS). MATERIAL AND METHODS This study included 290 undergraduate medical students (140 men, 150 women) from 4 different grades. Demographic characteristics and perceived stress scale (PSS) were measured using a pre-validated scaled questionnaire. The DMFS for each individual was measured intraorally. Continuous variables were expressed as means, and categorical variables as frequencies. Using Pearson correlation, the types and strengths of the relationships between stress levels and DMFS scores were determined (positive, negative, linear, nonlinear). All differences were considered significant at a P value of less than 0.01 (P<0.01). RESULTS A higher percentage of participants had moderate stress (73.8%), with higher PSS scores among female participants (m=21.52) than male participants (m=20.43). Participants with higher stress scores (27 to 40) had very high DMFS scores (4.5 to 6.5). Age had a negative association with stress (r=-0.072, P=0.219) and DMFS (r=-0.023, P=0.695) scores. No significant differences in scores indicated no significant linear link between the variables. A significantly positive linear correlation was observed between stress and DMFS scores (r=0.41, P=0.000), although the correlation was weak. CONCLUSIONS Undergraduate medical students perceive stress during their training. Level of stress was associated with severity of dental caries.