INCLUSION CRITERIA: Participants must meet the following criteria for inclusion in the trial:

• Must sign and date the informed consent form
• At least 18 years of age
• Documented diagnosis (endoscopic, surgical or x-ray) of ulcerative colitis
• Mild to moderate ulcerative colitis indicated by Disease Activity Index score of greater than or equal to 4 and less than or equal to 10
• Unless the patient is intolerant of oral 5-ASA therapy, patient must be treated with a minimum of 2 gm daily of an oral 5-ASA agent for a minimum of 4 weeks during the current exacerbation of ulcerative colitis or immediately prior to study entry
• If treated with oral corticosteroids, dose must not exceed 20 mg per day of Prednisone or equivalent
• If treated with corticosteroids, dose must be stable for 4 weeks prior to study entry and remain on same dose throughout
• If treated with 6-mercaptopurine or azathioprine, must have been on medication for 4 months and a stable dose for 2 months prior to study entry
• If a female of childbearing age, the participant must have a negative serum pregnancy test and have been using a medically approved form of contraceptive birth control for 3 months prior to enrollment. Participants, both male and female, must also be willing to use medically approved contraceptive birth control (at least one barrier method) throughout the study
• If treated with rectal therapy, dose must be stable for 2 weeks prior to study entry and remain on same dose throughout

EXCLUSION CRITERIA: Participants will be ineligible for participation in the trial if they meet any of the following criteria:

• Severe ulcerative colitis indicated by Disease Activity Index score of greater than 10
• Class III or IV congestive heart failure by NYHA classification system
• Allergy to thiozolidinediones
• Presence of any medical condition with an expected survival of less than 1 year
• Participants receiving therapy with cyclosporin, anti-TNF therapy, or methotrexate within the last 2 months of screening
• Positive stool culture for enteric pathogens (salmonella, shigella, and campylobacter), positive C.difficil toxin, or positive stool ova and parasite exam
• Positive proteinuria by urine dipstick
• History of chronic liver disease or baseline liver chemistries greater than the upper limit of normal
• Diabetes mellitus requiring hypoglycemic agents
• Participation in study of experimental therapy within 2 months of first screening visit
• Has any of the following laboratory abnormalities: WBC < 3,000 per uL, Neutrophil < 1,000 cell/cu.mm, Platelets <75,000 per uL, INR > 1.2
• Participant is female and is pregnant or currently breastfeeding