Inhalation medication is essential in the treatment of asthma and chronic obstructive pulmonary disease (COPD) patients. Incorrect inhalation technique reduces the effects of medication and has been reported to range from 22% to 95% from optimal. The objective of this study was to determine inter- and intraobserver reliability in inhalation technique assessment. For interobserver reliability three observers scored after three times viewing a total of 49 video recorded inhalation demonstrations using device-specific checklists and mutually agreed scoring rules. Intraobserver reliability was assessed for two observers after 8 months by scoring inhalation demonstrations a second time. Both inter- and intraobserver reliability were expressed by mean percent agreement and mean Kappa scores. All inhaler devices revealed a high mean percent agreement and a substantial or almost perfect Kappa scoring for both inter- and intraobserver reliability. Only one item, "exhale to residual volume," showed poor intraobserver reliability. Assessment of video recorded inhalation technique using device-specific checklists, triple viewing, and mutual agreed scoring rules is reliable. This method enables blind observation of inhalation technique.