Objectives: To evaluate the effectiveness of including interactive video-based patient cases in preparatory lectures on medical students' patient-centredness and attitudes towards psychiatry. Methods: This study was designed as a quasi-experimental intervention study. A preparatory lecture on diagnostic interviewing was given to 204 fourth-year medical students before a 4-week psychiatry clerkship. The students were divided into two groups. One group (n=102) received a preparatory lecture including an interactive video case portraying a doctor performing a diagnostic interview with a simulated patient (intervention group). The other group (n=102) received a conventional preparatory lecture using text-based instructional material (control group). We conducted a paired sample t-test to compare the students' confidence in exhibiting patient-centred communication and their attitudes towards psychiatry before receiving the preparatory lecture and after having completed a minimum of three weeks of clerkship training Results: A total of 102 students, 51 in each group, completed a questionnaire at both measurement points. In the intervention group, we found a statistically significantly difference for the students' patient-centredness before (M=69.4, SD=10.0) and after (M=73.8, SD=8.6) the intervention t(97)=2.38, p= 0.02, but no changes in attitudes t(98) =1.07, p=0.28. In the control group, we found no changes in patient-centredness or attitudes. Conclusions: Video cases in preparatory lectures appear to be better than text-based material at improving students' patient-centredness in psychiatry. However, neither video cases nor text-based material seem to influence the students' attitudes.