OBJECTIVES: Global clinical guidelines recommend fixed-dose combinations (FDCs) of inhaled corticosteroids (ICS) and long-acting beta agonists (LABA), delivered via an inhaler, as a treatment for moderate to severe persistent asthma and chronic obstructive pulmonary disease (COPD).  Poor inhalation technique – measured as the occurrence of critical inhaler errors ­– is common with existing inhalers, and may contribute to the economic burden of disease management by increasing healthcare resource use.  We have developed an economic model to evaluate the clinical and economic burden of asthma and COPD in the UK, and assess the impact of poor inhalation technique with ICS + LABA FDCs on costs and resource use.  METHODS: The eligible adult patient population was based on current confirmed asthma and COPD diagnosis rates in the UK, with the proportion of patients receiving FDCs based on available market research data.  Costs of inhalers, scheduled care and unscheduled healthcare events were taken from publically available sources in the UK.  Frequency of poor inhalation technique – measured through the occurrence of critical inhaler errors – and the associated increased risk of unscheduled healthcare events were taken from a large (n=1,664) cross-sectional, observational study in Italy.  RESULTS: The model estimated that 1.3 million adults with persistent asthma and COPD receive an ICS + LABA FDC in the UK, annually; of which, 366,000 demonstrate poor inhalation technique.  Total direct costs were estimated to be £875 million, with costs of unscheduled healthcare events accounting for £137 million.  Poor inhalation technique with ICS + LABA FDCs was estimated to be responsible for 11.8% of unscheduled healthcare costs, equating to £16.2 million annually.  CONCLUSIONS: The clinical and economic burden associated with poor inhalation technique in asthma and COPD is considerable in the UK.  Novel inhalers, which improve inhalation technique, may offer clinical and economic benefits in the management of asthma and COPD.