['\u2002 Video is a popular tool in problem-based learning (PBL), although its production requires resources and time. Few studies have examined the impact of the use of video in PBL upon cognitive processes and critical thinking. Those that have done focused on cases involving physical signs, where video has natural advantages.', "\u2002 This study aimed to investigate preferences for video- or text-based cases and the effects of each format upon medical students' deep thinking in PBL. Tutorials were based on material portraying interviews with patients with conditions that include psychosocial elements but no physical signs.", '\u2002 Four tutorial groups of students in a Year 2 endocrine and reproductive pathophysiology course participated in a crossover study using one video-based and one text-based case. Transcripts of tutorials were coded for depth of thinking by a blinded coder. A generalised estimating equation model was used to adjust for potential differences among groups, cases, and tutor participation. The distribution of cognitive activity within the crossover groups and the adjusted odds ratios (ORs) for deep versus superficial thinking were calculated. A prior cohort of 165 students and 18 tutors completed a survey of learning preferences.', '\u2002 Of 5224 student utterances, the majority referred to problem exploration (2622, 50%) and description (1479, 28%). Overall, the odds of deep thinking versus superficial thinking were significantly lower using video-based cases compared with text-based cases (2045 deep/2454 for video versus 1961 deep/2218 for text; OR 0.663, 95% confidence interval [CI] 0.582-0.754; p\u2003<\u20030.0001). This was also true for the problem exploration domain (1217 deep/1365 for video versus 1178 deep/1257 for text; OR 0.559, 95% CI 0.355-0.882; p\u2003=\u20030.0125). The majority of students (59%) and tutors (78%) indicated a preference for video-based cases over text-based cases.'] Do video-based cases disrupt deep critical thinking in problem-based learning?