The purpose of this study is to evaluate the effectiveness and safety of anti-TNF chimeric monoclonal antibody (cA2) compared to placebo in the treatment of patients with fistulizing Crohn's disease.

This is a randomized, placebo-controlled, double-blind, repeated-dose study to evaluate the effectiveness and safety of anti-TNF chimeric monoclonal antibody (cA2) compared to placebo in the treatment of patients with fistulizing Crohn's disease. The primary efficacy outcome of the study is the number of patients with at least a 50% reduction from baseline in the number of open fistulae observed for at least two consecutive evaluation visits.

Patients will be treated with either anti-TNF chimeric monoclonal antibody (cA2) or matching placebo.

Inclusion Criteria:

• Patients with Crohn's disease of at least 3 months duration confirmed by radiography orendoscopy
• Having single or multiple draining enterocutaneous (including perianal) fistulae of at least 3 months duration
• If treated with oral prednisone (or equivalent), the dose must be <=40 mg/day and must have been stable for at least 3 weeks prior to enrollment. (If currently not treated with oral prednisone, the stop date must have been at least 4 weeks prior to enrollment)
• If treated with 6-mercaptopurine or azathioprine, the start date must have been at least 6 months prior to enrollment. (The dose must have been stable for at least 8 weeks prior to enrollment. If currently not treated with 6-mercaptopurine or azathioprine, the stop date must have been at least 4 weeks prior to enrollment.)

Exclusion Criteria:

• Patients with local complications of Crohn's disease such as strictures or abscesses that might confound the evaluations of the benefit from cA2 treatment
• Having abscesses that should be drained prior to enrollment, with at least 3 weeks between drainage of the abscess and enrollment
• Having a serious infection, such as hepatitis, pneumonia or pyelonephritis, in the previous 3 months or a history of opportunistic infection such as herpes zoster within 2 months prior to screening, or evidence of active cytomegalovirus, active pneumocystis carinii, or drug resistant atypical mycobacterium
• Currently having signs or symptoms of severe, progressive or uncontrolled renal, hepatic, hematologic, endocrine, pulmonary, cardiac, neurologic or cerebral disease
• Currently having any known malignancy or any history of malignancy within the past 5 years