In spite of remarkable advances in teaching and developing new technologies, textbooks have a very crucial effect in the process of language teaching and learning. This paper evaluates the first year English textbook which is taught in Iranian high schools. For this purpose, textbook evaluation model was employed to conduct the research. The advantages and shortcomings of the textbooks are discussed in detail with reference to 13 common criteria extracted from different material evaluation checklists. The results suggest that one of the main factors for the students’ achievement in English language is the ELT textbooks. Throughout the study, Iranian first year high school English textbook was examined with reference to the relevant theoretical background, and the content analysis. The study was carried out at four schools in Tabriz, Iran. The mixed method, a combination of both quantitative and qualitative approaches was used in this study. The data were obtained from a total of 126 language learners, both female and male. It was collected through a questionnaire with 34 close-ended questions which were related to the seven sections of the book including the layout or physical make-up, vocabulary, topics and content, grammar points and exercises, language skills, pronunciation practice, and language function and social and cultural activities. Quantitative data were analyzed through SPSS. Meanwhile, qualitative data were gathered via interview with 14 teachers and selected students. It is realized that there should be enough opportunities for learners to practice the language communicatively. The research findings make it clear that the current material or textbook cannot meet the Iranian students’ and teachers’ needs and they are not acceptable and desirable for them. It can be concluded that the English textbook 1 is structure-based. So, the writers of the book should modify it by employing more communicative tasks in order to meet the teachers’ expectations and students’ needs.