A Randomized, Double-blind, Parallel Group Trial Comparing 12 Weeks Treatment With Tiotropium 18 mcg Daily to Combivent MDI 2 Actuations Qid in COPD Patients Previously Prescribed Combivent MDI

Inclusion Criteria: Diagnosis of Chronic Obstructive Pulmonary Disease (COPD) Age: greater than or equal to 40 years

* Current or ex-smoker with a \>= 10 pack-year smoking history

* Use of Combivent® Metered Dose Inhaler (MDI)for \>= 1 month prior to Visit 1

Spirometric criteria (determined at study visits):

* Post-bronchodilator Forced Expiratory Volume in one second (FEV1) \<= 70% (Visit 1)

* Pre-bronchodilator FEV1 \<= 65% of predicted and FEV1/Forced Vital Capacity (FVC) \<= 70% (Visit 2)

Exclusion Criteria:

Clinical history of asthma

* History of thoracotomy with pulmonary resection

* History of Cystic Fibrosis, alpha 1 antitrypsin deficiency or interstitial lung disease

* Daytime use of oxygen therapy for \> 1 hour per day or if unable to abstain fr om using oxygen during Pulmonary Function Tests

* Any respiratory tract infection or COPD exacerbation in 6 weeks prior to Visit 1

* Recent history 6 months or less of Myocardial Infarction

* Unstable or life-threatening cardiac arrhythmias

* Hospitalization for Congestive Heart Failure during past year

* Malignancy for which patient is receiving chemo or radiation therapy

* Pregnant or nursing women

* Known hypersensitivity to ipratropium or carrier substances, including related food products such as soybean, peanuts, or lactose

* Use of SPIRIVA® 3 months prior to Visit 1

* Symptomatic of prostatic hypertrophy or bladder neck obstruction

* Known narrow- angle glaucoma

* Participating in a pulmonary rehab program within 4 weeks of Visit 1