This study examines one of the most important social concepts and perspectives in mathematics textbooks from first grade to 12th grade in Palestine, which is gender bias. To achieve the goal of this study, the researcher conducted a quantitative and qualitative content analysis of an interval sample of these textbooks. Content analysis is considered an important method for revealing the strengths and weaknesses of curriculum components. The content analysis addressed the use of gender in names, verbs (actions), pictures, pronouns, and professions. The result confirms a male bias in all aspects of the analysis. The same result was confirmed by the qualitative analysis of profession types mentioned in mathematics textbooks for both females and males. In light of these results, the researcher strongly recommends that the curriculum be reformed to improve the gender balance.