INTRODUCTION: Improving health-related quality of life (HRQoL) in COPD patients is an important pharmacotherapeutic objective. This study investigated the extent, consistency, and durability of tiotropium maintenance therapy impact on HRQoL in moderate-to-very severe COPD. METHODS: Patients received once-daily tiotropium 18 μg (n = 5244) or placebo (n = 4799) via HandiHaler(®) (10 trials), or once-daily tiotropium 5 μg (n = 2622) or placebo (n = 2618) via Respimat(®) inhaler (3 trials). St George's Respiratory Questionnaire (SGRQ) total scores were measured at baseline, and 6 months (13 trials) and 1 year (9 trials) from treatment start. Adjusted mean differences between treatments for change from baseline in total scores were calculated at each time-point for each trial. Responder and deteriorator rates (decrease or increase in score ≥4 units from baseline, respectively), net benefit (responder rate increase plus deteriorator rate decrease), and cumulative improvement and deterioration were determined. RESULTS: Adjusted mean total score differences between treatments for change from baseline were significant (p