Purpose: The objective of this study was to measure the improved ethical reasoning capability regarding interprofessional collaboration of undergraduate medical and nursing students with PBL of clinical ethics curriculum. Methods: 50 volunteered medical and nursing students were divided into six groups. Two rich narrative stories with detailed descriptions of the interactions and conversations were used in the PBL tutorials. The interprofessional ethics education (IPEE) measurement was used to evaluate interprofessional ethical knowledge, ethical value judgments, and ethical reasoning ability at pre- and postcurriculum level. The responsiveness of the outcome was assessed by paired t-test, and Effect Size (ES). Multivariable analysis was used to compare the responsiveness of the outcome between medical and nursing students. Results: The post-curriculum score of ethical case analysis of medical students increased significantly (p = 0.0078, ES = 1.27), while the score of ethical scenario testing of nursing students increased significantly (p = 0.0096, ES = 0.58). Moreover, the change in score of ethical scenario testing in nursing students was more signifi cant than that in medical students by 0.60 points (p = 0.0190). After interprofessional learning, the number of medical and nursing students with extreme opinions on the value judgments of the ethical scenarios was decreased, and the disagreement of the originally different professions was gradually resolved. Conclusions: The interprofessional PBL curriculum of clinical ethics can improve students' capability of interprofessional collaboration, value judgments of ethical scenarios, and ethical reasoning ability. In addition, while the IPEE assessment tool may be suitable for measuring such effect, it must be modified for related studies to choose.