 The primary objective of this study is to compare the effect of ipratropium bromidesalbutamol inhalation spray combination administered by the Respimat inhaler 20 mcg100 mcg, ipratropium bromide inhalation spray administered by the Respimat inhaler 20 mcg, and COMBIVENT MDI administered q.i.d on FEV1 at intervals over a treatment period of 12 weeks in patients with COPD. Specifically, non-inferiority of Combivent Respimat to COMBIVENT MDI in FEV1 AUC from 0 to 6 hours , superiority of Combivent Respimat to Atrovent Respimat monotherapy in FEV1 AUC from 0 to 4 hours, and non-inferiority of Combivent Respimat to Atrovent Respimat monotherapy in FEV1 AUC from 4 to 6 hours will be analyzed. In addition, steady state pharmacokinetics over one dosing interval following 4 weeks of therapy will be characterized in a subgroup of patients. 