Introduction: The widespread developments of the twentyfirst century have been accompanied by the presentation of intellectual patterns and theories and new achievements. These new achievements emphasize the skill of thinking at high levels, especially in the educational system of universities. This skill is essential for medical students; therefore, the present study aimed to investigate the qualitative barriers of critical thinking in medical students’ curriculum. Methods: This is a qualitative study in which the content analysis method has been used. Participants of this study included 11 medical education experts and medical students (6 females and 5 males) who were selected through a semi-structured interview and purposeful sampling. The data analysis method was conventional content analysis. In the next part, by more investigation of the data, various obtained concepts will be presented in the form of themes, categories, and subcategories. Results: We obtained two themes (socio-cultural conditions and traditional and unchanging system of education), eight categories and 14 subcategories. Also, these categories were resistance to critical society, intellectual tension, personality characteristics, lack of understanding of society’ s need for criticism, the rule of traditional teaching pattern, lack of critical thinking skills, ineffective evaluation, and difficulty of critical thinking training. Conclusion: Given the results and the main emphasis of curriculum planners on incorporating high-level critical thinking and revision skills into the curriculum, the country’ s academic education system requires a change in the thinking style, research, deepening critical thinking, and a change in teachers’ attitudes toward curriculum designing (goals, content, teaching and evaluation methods); also, it is suggested that the authorities should pay attention to the need to develop and utilize critical thinking skills in the learners’ education.