This is an open-label, phase IV trial. Adult patients, with moderately to severe, steroid dependent, acute ulcerative colitis not previously exposed to anti-TNF, will receive subcutaneous golimumab treatment, according to EU marketing authorization from baseline through week 14.||At week 16, patients achieving clinical and endoscopic remission will continue with Golimumab, 50 mg or 100 mg (depending on body weight) every 4 weeks, through week 52.||Patients not achieving clinical and endoscopic remission will be treated with infliximab, according to marketing authorization, and followed through week 52. This is not considered as an interventional arm but, since infliximab in Italy is considered as the first-line treatment for UC patients, as the usual clinical practice.