The purpose of this study is to evaluate the effectiveness and safety of infliximab (Remicade) in patients with Ulcerative Colitis. Infliximab (Remicade) targets specific proteins in the body's immune system to help control the development of inflammation to help reduce painful disease.

This study is designed to investigate the safety and effectiveness of infliximab in adult patients with active ulcerative colitis. The purpose of this study is to see if the symptoms of ulcerative colitis are lessened with this medication infliximab, and what dose is needed to do that safely.Patients will receive infusions of either 5 or 10 mg/kg or placebo at weeks 0, 2, 6, 14, and 22 up to week 164. Safety evaluations will be performed at specified intervals throughout the study and will consist of laboratory tests, vital signs (such as blood pressure), physical examinations and the occurrence and severity of adverse events as well as other study specific procedures.

Patients will receive infusions (into the vein) of either 5 or 10 mg/kg or placebo at weeks 0, 2, 6, and every 8 weeks up to week 164.

Inclusion Criteria:

• Patients must have had ulcerative colitis of at least 3 months' duration at screening, confirmed by the biopsy taken at screening
• Patients must have active colitis confirmed during the screening sigmoidoscopy
• Patients must have active disease.

Exclusion Criteria:

• Patient must not be likely to require surgical removal of all or part of the colon within 12 weeks of beginning the study
• Patient must not require, or required within the 2 months prior to beginning the study, surgery for active gastrointestinal bleeding, peritonitis, intestinal obstruction, or intra-abdominal or pancreatic abscess requiring surgical drainage