BackgroundProblem-based learning (PBL) is a widely adopted educational approach in medical education that aims to promote critical thinking and problem-solving in authentic learning situations. However, the impact of PBL educational mode on undergraduate medical students’ clinical thinking ability has been limitedly investigated. This study aimed to assess the influence of an integrated PBL curriculum on clinical thinking ability of medical students prior to clinical practice.MethodsTwo hundred and sixty-seven third-year undergraduate medical students at Nantong University were recruited in this study and were independently assigned to either the PBL or control group. The Chinese version of the Clinical Thinking Ability Evaluation Scale was used to assess clinical thinking ability, and the students’ performance in the PBL tutorials was assessed by tutors. All participants in both groups were required to complete the pre-test and post-test questionnaires to self-report their clinical thinking ability. A paired sample t-test, independent sample t-test and one-way analysis of variance test (ANOVA) were used to compare the difference in clinical thinking scores among different groups. Multiple linear regression was conducted to analyze the influencing factors correlated with clinical thinking ability.ResultsThe clinical thinking ability of most third-year undergraduate medical students at Nantong University was at a high level. The PBL group had a higher proportion of students with high-level clinical thinking ability in the post-test compared to the control group. The pre-test scores of clinical thinking ability were similar between the PBL and control groups, but the post-test scores of clinical thinking ability in the PBL group were significantly higher than those in the control group. Additionally, there was a significant difference in clinical thinking ability between the pre-test and post-test in the PBL group. The post-test scores of sub-scales of critical thinking ability were significantly higher than the pre-test in the PBL group. Furthermore, the frequency of reading literature, time of PBL self-directed learning, and PBL performance score ranking were influencing factors on the clinical thinking ability of medical students in the PBL group. Moreover, there was a positive correlation between clinical thinking ability and the frequency of reading literature, as well as the scores of the PBL performance.ConclusionsThe integrated PBL curriculum model has an active impact on improving undergraduate medical students' clinical thinking ability. This improvement in clinical thinking ability may be correlated with the frequency of reading literature, as well as the performance of the PBL curriculum.