Rapidly changing developments and expanding roles in healthcare environment requires professional nurses to develop critical thinking. Nursing education strives to facilitate students' critical thinking through the appropriate instructional approaches. Problem-based learning (PBL) is a student-centered approach to learning which enables the students to work cooperatively in small groups for seeking solutions to situations/problems. The systematic review was conducted to provide the available evidence on developing nursing students' critical thinking through PBL. The computerized searches from 1990-2006 in CINAHL, Proquest, Cochrane library, Pubmed etc were performed. All studies which addressed the differences in critical thinking among nursing students in PBL were considered. Two independent reviewers assessed the eligibility of each study, its level of evidence and the methodological quality. As a result, only ten studies were retrieved, they were: one RCT with a Jadad quality score of 3, one nonrandomized control study, two quasi-experimental studies with non-controlled pretest-posttest design, and six descriptive studies. The available evidence in this review did not provide supportive evidence on developing nursing students' critical thinking through PBL. Clearly, there is a need for additional research with larger sample size and high quality to clarify the effects of PBL on critical thinking development within nursing educational context.