It is generally observed that the textbooks employed in the classroom play a crucial role in the process of teaching and learning. In the EFL context in Iran, where Iranian EFL learners rarely have access to native speakers, the teacher mediates between the learner and the text. Accordingly, a textbook plays more important roles in this context and textbook evaluation is critical. Nowadays, under the influence of Communicative Language Teaching (CLT), most global materials try to involve learners in the process of learning by introducing several types of tasks and activities whose aim is to promote learners’ interaction. However, most teachers and instructors are using the global materials without being aware of the task types used in them and whether these task types really involve learners in the communication process or not. The purposes of this study was to evaluate and compare the two most popular global course books (Top Notch and Interchange) which are taught in Iranian ELT institutes, in terms of their task types according to Nunan’s (1999) classification of the tasks. The results suggested that generally, both course books used mostly linguistic tasks and less cognitive ones. However, in particular, the number of co-operative tasks in Interchange title is more frequent than other types of tasks, while in Top Notch title most of tasks are practice tasks. The results of this study could be helpful for curriculum developers and institute authorities, to assist them to become more aware of different task types used in each of these global materials and to better select the most suitable ones for their purposes. It can also help material developers in order to develop ELT materials with more communicative tasks