Objective: To determine if improvement in patients’ metered dose inhaler (MDI) technique could be achieved in the emergency department (ED) with the use of a simple illustrated instruction sheet. Methods: Prospective evaluation of a convenience sample of patients with asthma or COPD. Patients were first subjectively and objectively evaluated on their usual MDI technique, then were given an illustrated instruction sheet to study for 5 minutes. There was no verbal coaching prior to the post-test. A post-test evaluation was then performed. Results were compared using paired Student t test. Results: A total of 115 patients were enrolled. Mean age was 34.9±13.1 years, and mean years using MDI was 5.7±3.8. Subjective improvement in technique was reported by 110 patients (96%) with a mean pre-test score of 7.4±1.5 and post-test score of 9.2±1.1 (p<0.0001, 10 point scale). Objective improvement was achieved in 113 patients (98%) with a mean pretest score of 3.9±1.3 and post-test score of 5.8±1.0 (p<0.0001, 7 point scale), corresponding to a 30% improvement in technique (95% CI: 22,39). Fortyfour patients (38%) reported never having been shown proper MDI technique by a health care professional, and 112 patients (97%) found the instruction sheet helpful. Conclusions: Rapid objective and subjective improvement of MDI technique from both patients’ and physicians’ perspective is possible in the ED with the use of an illustrated instruction sheet, and requires minimal effort from the treating emergency physician.