To date, there have been no formal clinical studies completed using tiotropium in CF patients. While there is a large body of evidence demonstrating the efficacy and safety of tiotropium in patients with Chronic Obstructive Pulmonary Disease (COPD), relatively little is known about its efficacy and safety in patients with a diagnosis of cystic fibrosis. Therefore, Boehringer Ingelheim proposed to profile the long acting anticholinergic tiotropium and to generate adequate clinical data for use as a bronchodilator in paediatric and adult CF. The phase III trial (205.438) is a part of the approved Paediatric Investigation Plan (PIP) agreed for Spiriva® Respimat® in Cystic Fibrosis.