A Study To Investigate The Safety And Efficacy Properties Of PF-00547659 In Patients With Active Ulcerative Colitis

Inclusion Criteria: * A positive histological diagnosis of UC ≥3 months prior to entry into the study. If a histological diagnosis is not available but all signs and symptoms suggest UC, the subject's eligibility should be discussed with Pfizer. * Active UC as defined by a score of ≥6 on the Mayo score. * An endoscopic (by flexible sigmoidoscopy) sub-score of ≥2 on the Mayo score determined within 7 days of first dosing. Exclusion Criteria: * Subjects with UC, which is confined to a proctitis on a flexible sigmoidoscopy. * Subjects who have had surgery as a treatment for UC or are likely to require surgery within the duration of the study. * Subjects displaying clinical signs of ischemic colitis.