Although images are abundant and play significant aesthetic and pedagogical roles in today’s EFL course books, they are still one of the less explored areas of research. The present study is an attempt to examine the role and function of images in Iranian high school EFL course books it also aims to cast a critical eye over their suitability and efficiency. To this end, Kress and Van Leeuwen’s (2006) model of visual grammar was adopted. The findings revealed that although the informative and/or illustrative functions of the images make them important resources in Iranian high school EFL course books, their full potential for language learning does not seem to be adequately exploited. This relates to flaws at the representational mode of meaning making, such as outdated portrayal of objects, gender stereotyping, and overdramatizing national identity as well as shortcomings at the interactive mode, such as poor modality due to grayscale printing and plain graphics with no contextualization or pictorial detail. These flaws make the images seem out of today’s world and hardly credible for high school students who are already adept at new technology. Since these shortcomings may sacrifice pedagogical objectives, the study calls for changes in both technical quality and underlying messages of images in the course books.