The present study was an attempt to investigate and compare the efficiency of the new and the old first grade high school English textbooks by focusing on thirty teachers and three hundred learners’ attitudes through a textbook evaluation checklist and a questionnaire. The analysis of the results revealed that, with regard to teachers' attitude toward the two books compared with each other, these books were nearly the same with regard to pronunciation and exercises. The old book was considered more efficient regarding grammar. Regarding the rest of the items, the new book was more efficient. Taking the learners perspective into account toward these two books compared with each other, there were no noteworthy difference between the books regarding vocabulary. Regarding the other items, the new book was considered more efficient. The findings of this study can assist decision-makers to pay more attention to the evaluation of textbooks and consequently the selection of an appropriate book according to the teachers and learners’ expectations, needs and interests.