Inclusion Criteria:
1. Participants had to be a male or female between the ages of 18 and 75 years old at the time of the Screening Visit.
2. Participants who had a diagnosis of ulcerative colitis (UC) greater than 90 days prior to baseline (week 0) and failed conventional treatment.
3. Participants diagnosis of active UC was confirmed by a colonoscopy with biopsy or flexible sigmoidoscopy with biopsy.
4. Participants who had active UC with a Physicians Global Assessment (PGA) score of 2 or 3 and Short Inflammatory Bowel Disease Questionnaire (SIBDQ) ≤ 45 at baseline (week 0).
5. Concurrent therapy was required for participants who were previously treated with corticosteroids or immunosuppressants (azathioprine (AZA) or 6-mercaptopurine (6-MP)) and, in the judgment of the investigator, had failed to respond to or could not tolerate their treatment. Participants had to be on a concurrent treatment with at least one of the following (oral corticosteroids or immunosuppressants or both as defined below):
* Stable oral corticosteroid dose (prednisone ≥ 20 mg/day or equivalent) for at least 14 days prior to baseline, or
* Stable oral corticosteroid dose (prednisone \< 20 mg/day) for at least 21 days prior to baseline, and/or
* At least a consecutive 12 weeks (84 days) course of AZA or 6-MP prior to baseline.
Exclusion Criteria:
1. Participants who had a history of subtotal colectomy with ileorectostomy or colectomy with ileoanal pouch, Kock pouch, or ileostomy for UC or planned bowel surgery.
2. Participants received previous treatment with adalimumab or previous participation in an adalimumab clinical study.
3. Participants who had previously used infliximab or any anti- tumor necrosis factor (TNF) agent within 56 days of baseline (week 0).
4. Participants who had previously used infliximab or any anti-TNF agent and had not clinically responded at any time ("primary non-responder") unless they experienced a treatment limiting reaction.
5. Participants who had received cyclosporine, tacrolimus, or mycophenolate mofetil within 30 days of baseline (week 0).
6. Participants who had received intravenous (IV) corticosteroids within 14 days of Screening or during the screening period.
7. Participants who had a current diagnosis of fulminant colitis and/or toxic megacolon.
