Aim: This research aimed to evaluate the effect of the psychodrama-based intervention used in the communication course of 2nd year nursing students on their therapeutic communication skills and cognitive flexibility., Background: Psychodrama has been defined as a way of practicing living without being punished for making mistakes. The psychodrama-based interventions can be used as a novel teaching method to improve therapeutic communication skills and cognitive flexibility in education by allowing students to learn from their trials and errors before going into clinical practice and communicating one-on-one with the patient., Design: A single group, pretest-posttest with a follow-up quasi-experimental design was adopted., Method: The participants were a convenience sample of 24 s-year undergraduate nursing students. Students attended a one-day in-a-week psychodrama-based communication course for 14 weeks. The data of the study were collected with the Demographic Information Form, the Therapeutic Communication Skills Scale and the Cognitive Flexibility Inventory. Outcomes were measured on the first day (baseline), at the end of the course and 6 and 12 months after completing the course. Outcomes were analyzed using descriptive and repeated measures analysis of variance, Friedman and Dunn tests., Results: It was determined that the nontherapeutic communication scores were significantly lower at the post-test, 6 months and 12 months than at baseline in participants. Therapeutic-one scores were significantly increased at the post-test compared with baseline in participants. Therapeutic-two scores were significantly increased at 6 months compared with baseline. There was no statistical difference in any measure in the cognitive flexibility inventory., Conclusion: The psychodrama-based intervention in communication course significantly improved nursing students' therapeutic communication skills. It is also recommended to conduct studies with larger samples of nursing students from different institutions and also randomized controlled studies with control groups and qualitative studies. It is recommended to conduct studies evaluating an intervention that includes subheadings more related to cognitive flexibility which is an important nursing competency, as well as new studies that evaluate cognitive flexibility with different measurement tools., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)