Recent communicative teaching approaches view learning English as a Foreign Language (EFL) as involving more than knowledge of grammar structures. Students are expected to develop communicative skills which allow them to interact inside and outside the language classroom. To this end, learning idioms plays a significant role because these expressions improve students' proficiency, fluency and native-like performance (Boers et al., 2006). However, even though they are beneficial for students' language skills, some teachers may decide to avoid teaching these expressions in the classroom. Motivated by this, the present study examines the perceptions of five Mexican EFL teachers concerning the teaching of English idioms. Semi-structured interviews reveal that the five teachers perceive that teaching idioms is highly important for developing students' communicative competence. However, the results also indicate that four teachers avoid teaching them because of institutional demands to cover a textbook and their perceptions of their students' low proficiency levels. This evidence suggests that pre- and in-service teacher education programs should provide teachers with a better understanding of strategies that they can use to teach idioms.