Background Previous research has demonstrated that patients leaving the emergency department (ED) have poor recall and understanding of their discharge information. The teach-back method is an easy technique that can be used to check, and if necessary correct, inaccurate recall. In our study, we aimed to determine the direct and short-term impact of teach-back as well as feasibility for routine use in the ED. Methods A prospective cohort study in an urban, non-academic ED was performed which included adult patients who were discharged from the ED with a new medical problem. The control group with the standard discharge was compared to the intervention group using the teach-back method. Recall and comprehension scores were assessed immediately after discharge and 2–4 days afterward by phone, using four standardized questions concerning their diagnosis, treatment, follow-up care, and return precautions. Results Four hundred eighty-three patients were included in the study, 239 in the control group, and 244 in the intervention group. Patients receiving teach-back had higher scores on all domains immediately after discharge and on three domains after 2–4 days (6.3% versus 4.5%). After teach-back, the proportion of patients that left the ED with a comprehension deficit declined from 49 to 11.9%. Deficits were most common for return precautions in both groups (41.3% versus 8.1%). Teach-back conversation took 1:39 min, versus an average of 3:11 min for a regular discharge interview. Conclusion Teach-back is an efficient and non-time-consuming method to improve patients’ immediate and short-term recall and comprehension of discharge information in the ED.