OBJECTIVES: We aimed to clarify the communication behaviors between trainee dentists and simulated patients (SPs), to examine how the level of trainee dentists' self-reported empathy influences assessment by SPs in medical interviews. MATERIALS AND METHODS: The study involved 100 trainee dentists at Okayama University Hospital and eight SPs. The trainee dentists conducted initial interviews with the SPs after completing the Japanese version of the Jefferson Scale of Empathy (JSE). All interviews were recorded and analyzed using the Roter Interaction Analysis System (RIAS). The SPs assessed the trainees' communication immediately after each interview. The trainee dentists were classified into two groups (more positive and less positive) according to SP assessment scores. RESULTS: Compared with less-positive trainees, the more-positive trainees scored higher in the RIAS category of emotional expression and lower in the medical data gathering category. There was no difference in dental data gathering between the two groups. SP ratings for more-positive trainees were higher for use of positive talk and emotional expression and lower for giving medical information and dental information. Trainees with more positive ratings from SPs had significantly higher JSE total scores. CONCLUSION: The results of this study suggest that responding to the emotions of patients is an important behavior in dentist-patient communication, according to SPs' positive assessment in medical interviews. Further, SPs' assessment of trainees' communication was related to trainees' self-reported empathy, which indicates that an empathic attitude among dentists is a significant determinant of patient satisfaction.