Currently, patients have to keep track of doses to determine when to replace their metered-dose inhalers (MDIs). This study evaluated the performance and patient satisfaction of a novel MDI with an integrated dose counter. In an open-label study at 38 outpatient centres, patients > or =12 years old with asthma or chronic obstructive pulmonary disease (COPD) received two actuations of fluticasone propionate/salmeterol 125/25 microg (115/21 microg ex-actuator) hydrofluoroalkane (ADVAIR) HFA) via MDI with counter twice a day until all 120 actuations were completed. Concordance between counter and diary recordings in patients who reported use of > or =90% of labelled actuations (completer population, n = 228) was high (discrepancy rate of 0.94%) and the incidence of device firing without changes in counter readings was low (0.13%). Mean expected actuations based on canister weights (114) were slightly lower than mean counter (121) and diary reported actuations (120). Upon study completion, 95% of patients were satisfied with the dose counter and 92% agreed it would help prevent them from running out of medication. Safety assessments (intent-to-treat population, n = 237) indicated that the drug was well tolerated. This integrated MDI counter may help patients maintain better disease control by enabling them to accurately track their medication supply.