Objective: To determine the rate of wrong - using of inhaled drugs and factors related to the techniques.Methods: This was a descriptive study. Researchers observed and collected data from a group of170 patients who were using inhaled drugs to treat chronic obstructive pulmonary disease (COPD) at theExamination Department of C Hospital from January to May 2019.Results: The number of patients who had a poor technique and were unknown how to use inhaled drugsaccounted for 77.1% for MDI inhalers and 70.5% for DPT inhalers perspectively. There was a statisticalsignificance between age, the period of illness, duration of joining the Asthma and COPD club, level ofairway obstruction, prescription, and errors in the techniques for using inhaled drugs. Conclusions: The hospital needs to maintain asthma and COPD club activities regularly to share and instructface-to-face about the techniques of using inhaled drugs for patients and their relatives. When instructing thepatient to use inhaled devices, medical staff should perform slowly and explain clearly on the model for patientsobserving, together with using a checklist to assess a skill level of the patients when they use the devices.