Purpose: This study was carried out to examine and compare the visual representations used in the biology units in 7th and 8th-grade middle school science textbooks with various criteria. Design/Methodology/Approach: A document review model from qualitative data analysis was used for this research. The content and descriptive analysis techniques were used in the analysis of the textbooks. The code list used in this study consisted of five main categories, which were type of visual representation, surface feature of visual representations, captions of visual representation, the relation of visual representation with text, and function of visual representation. Findings: As a result, visuals were used in different varieties and proportions according to the examined categories in both textbooks. The most common type of use was picture, followed by diagram. The examined rates of other subcategories of the categories were displayed in separate tables, as they showed differences at each grade level of the biology units. Highlights: When the findings were examined, it was found that the designs of the visuals in both textbooks and their relationships with the text were not sufficient to comprehend the biology subjects. For this reason, the biology content in these textbooks should be designed by taking into account the students' cognitive learning system, readability, and meaningful learning.