It is estimated that up to 70-90% of asthma and COPD patients use their Metered Dose Inhalers (MDIs) incorrectly. However, clinicians often fail to detect patients’ incorrect MDI technique by observation alone. In this study, we quantitatively examined the accuracy of MDI technique of 23 physician-diagnosed asthma and COPD patients in an outpatient clinic setting using CapMedic, an electronic MDI technique-monitoring tool (Cognita Labs, Houston, TX). We used these quantitative data to determine accuracy and limitations of the current practice that empirically assess MDI use by observation alone.