Introduction: To live successfully in a democratic society, people should be able to think critically in order to make correct personal and social decisions when encountering problems. If students learn to think critically they will find a guide to live more lively. The first priority in educational centers is to train students to think critically. Materials and Methods: The aim of this descriptive and analytic study is to evaluate critical thinking in freshmen and senior students of Payam-e-Nour University. 60 Students were selected by the purposeful sampling method and to measure their critical thinking, the CCTST form-B questionnaire was used. Data were analyzed using t and variance tests. Results: There was no significant difference between the total critical thinking scores in freshman and senior students, but the difference was significant regarding evaluation scores between the two groups (P value=0.017). Conclusion: since critical thinking is highly valued, appropriate educational methods should be implemented in higher education programs.