Background: Today, the development of critical thinking is considered an expected outcome of graduate studies. This study was designed to determine the critical thinking skills of students of Shahid Beheshti and Tehran University of Medical Sciences.

Materials and methods: In a descriptive study, evaluated critical thinking skills of 60 medical students of Shahid Beheshti University of Medical Sciences and 60 medical students of Tehran University of Medical Sciences, after completing internship. Data was gathered using California standard test of critical thinking skills (form B) which was run officially. The data was analyzed by SPSS software using T-test, ANOVA and Pearson correlation coefficient.

Results: The mean and standard deviation of critical thinking scores for medical students of Shahid Beheshti and Tehran University were 13.03 ± 5.08 and 12.63 ±3.27, respectively (p>0.05). There was no significant relationship between the ranks in University entrance exam and total score of critical thinking. Among domains of critical thinking, there was just significant relationship between the domains of deductive reasoning and diploma grade, with a relatively low correlation in medical students.

Conclusion: The mean scores of critical thinking skill in this research was similar to scores of some survey in our country, but were lower than other countries. This means that the educational program cannot promote critical thinking skills in University and revising the curriculum seems necessary.

Keywords: Critical thinking skills, Medical student, Rank of University entrance exam, Diploma grade.