This paper aims to analyze gender bias in the Islamic education school textbooks- Grade 3 used in all public schools in Oman. Quantitative and qualitative content analyses are used to investigate the following categories: images, occupational roles, names, adjectives, and gender firstness. Study findings show that gender bias is still strongly visible and ingrained in the four Islamic education school textbooks used in Grade 3. Men were dominant in almost all school textbooks. Men, for example, were strongly more visible than women in the following categories: images, occupational roles, names, and gender firstness in most textbooks. Women, on the other hand, were more visible than men in only one Islamic education textbook (Part 1, Semester 2) in the category related to gender firstness. The study findings also show that traditional occupational roles of men and women are still present in textbooks. In general, the Islamic education school textbooks used in all public schools in Oman confirm the findings of other previous studies in terms of the presence of gender bias against women in school curricula. The findings of the present study should help book writers promote gender equality and fight gender-biased against women in school textbooks around the world. This paper aims to analyze gender bias in the Islamic education school textbooks- Grade 3 used in all public schools in Oman. Quantitative and qualitative content analyses are used to investigate the following categories: images, occupational roles, names, adjectives, and gender firstness. Study findings show that gender bias is still strongly visible and ingrained in the four Islamic education school textbooks used in Grade 3. Men were dominant in almost all school textbooks. Men, for example, were strongly more visible than women in the following categories: images, occupational roles, names, and gender firstness in most textbooks. Women, on the other hand, were more visible than men in only one Islamic education textbook (Part 1, Semester 2) in the category related to gender firstness. The study findings also show that traditional occupational roles of men and women are still present in textbooks. In general, the Islamic education school textbooks used in all public schools in Oman confirm the findings of other previous studies in terms of the presence of gender bias against women in school curricula. The findings of the present study should help book writers promote gender equality and fight gender-biased against women in school textbooks around the world.