Background and Objective: Critical thinking has always been at the forefront of the global education system as purposeful thinking.This study aimed to investigate critical thinking as one of the mental health dimensions in elementary textbooks in the form of a quantitative and qualitative content analysis. Materials and Methods: This study was a descriptive research and the methods of library and content analysis were used. The study sample included all primary school textbooks in the academic year 2017-2018. The main source of determination of the components of mental health was the comprehensive curriculum of health education in schools from preschool to the end of highschool, which was revised according to the opinion of eight experts in the field of mental health. Data collection method, identification, analysis and counting the components of each of the analysis unit text, image and activity were based on the list of analysis content. For quantitative analysis of the data, descriptive statitsics, frequency calculation was used. Results: Among the components of critical thinking, the ability to analyze information and experiences, and unbiased judgments, had the highest and lowest frequencies, respectively. The highest frequency of critical thinking components was found in the sixth grade textbooks and the least frequency was in the third grade. Based on the form of presentation, the highest frequency of critical thinking material was in form of excersices and the least was among materials in the form of image. In addition, the most attention has been drawn to the knowledge-based materails while skill-based materails had received no attention. Conclusion: It can be concluded that little attention has been paid to critical thinking in primary school textbooks, and the main focus of the presentation is in the knowledge axis while the skill axis has received improper attention. Ethical code: IR.IUMS.REC.1396.31793 DOI: http://doi.org/10.22037/ch.v4i4.24193