One of the difficult tasks in English for Specific Purposes (ESP) classes is helping students to retain terminology of their fields of study. This is especially true in medical classes at a medical college in the Mekong Delta where students have very low level of English proficiency. The current study applied the use of authentic materials in teaching medical terminology to 250 EFL students majoring in pharmacy and nursing. Data on their perception toward the effects of using authentic materials on medical English terminology retention were gained from questionnaires. The study findings reveal some useful implications for teachers of ESP classrooms in the Mekong Delta in specific and in Vietnam in general.