In recent years, there has been a growing interest in using concordance lines as part of corpus-based language pedagogy to enhance vocabulary instruction. However, teachers in various L2 teaching contexts may lack awareness on how to design and use concordance lines while teaching vocabulary, and they may need guidance in order to implement corpus-based language pedagogy effectively in their actual teaching practices. Based on this need, the present study aimed at offering in-service training on the design and implementation of corpus-based materials in vocabulary instruction, and exploring teachers' perceptions of using these materials in their classrooms. For these purposes, three EFL instructors at a Turkish state university participated in the study. Participants received a four-week training on corpus-based language pedagogy, the use of corpus in L2 vocabulary learning and how to design and implement concordance lines to enhance their instruction. Data were collected through semi-structured interviews, reflective logs and an open-ended questionnaire. Qualitative analyses revealed that EFL university instructors did not have prior knowledge about how to use corpus-based materials in vocabulary instruction before the study, and training increased their awareness on incorporating corpus-based language pedagogy into vocabulary instruction. Moreover, the participants perceived the implementation of the corpus-based materials beneficial for raising students' awareness on specific vocabulary items as well. Nevertheless, the participants stated their concerns regarding the use of corpus-based language pedagogy due to challenges in using technology and designing corpus-based materials. The findings of this study may shed light on teachers' classroom practices of corpus-based language pedagogy in vocabulary instruction.