Gender bias is unfortunately still present in many societies especially the developing countries. Such prejudice is in most cases in favor of males and against females. While females nowadays comprise a great majority of the work force all around the world, they are still being looked upon as the weaker sex associated with stereotypical roles as stay-at-home mothers whose main task is to breed children, wash the dishes, etc.Such prejudice if present in a society gets manifested in its EFL/ ESL materials. The main purpose of the present study is to examine the extent and types of gender bias in two of the Iranian mostly used EFL textbooks at the high school level. Sexism will be investigated in five categories of visibility, firstness, generic masculine constructions, sex-linked occupations and activities. The findings are expected to raise awareness regarding sexist practices in EFL material developers, teachers and learners.