Background: A considerable number of children with asthma remain symptomatic despite treatment with inhaled corticosteroids, resulting in significant morbidity, reduced quality of life, increased healthcare costs and lost school days. The aim of our study was to assess the efficacy, safety and tolerability of once-daily tiotropium Respimat? 5??g, 2.5??g and 1.25??g add-on to medium-dose inhaled corticosteroids, with or without a leukotriene modifier, in children aged 6?11 years with symptomatic asthma. Methods: In this Phase II, double-blind, placebo-controlled, incomplete-crossover, dose-ranging study, patients were randomised to receive three of the four treatments evaluated: once-daily tiotropium Respimat? 5??g, 2.5??g or 1.25??g or placebo Respimat?, in the evening during the 12-week (...