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.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.Adjusted mean total score differences between treatments for change from baseline were significant (p < 0.05) in favor of tiotropium in 10/13 trials at 6 months and in 8/9 trials at 1 year. In all trials, estimated differences in responder rates between treatments favored tiotropium (significant [p < 0.05]: 5/13 trials at 6 months; 8/9 trials at 1 year). Net benefit favored tiotropium and cumulative improvement rates were consistently greater and deterioration rates consistently lower for tiotropium versus placebo.Tiotropium maintenance therapy significantly and consistently improved HRQoL in moderate-to-very severe COPD patients in a durable manner. These results may provide a benchmark for assessing benefits on HRQoL of other COPD treatments.