The primary objective of this registry is to collect long-term (5 years) safety data, including data on the incidence of colorectal cancer, in subjects with moderate to severe active ulcerative colitis (UC) who
have been exposed to infliximab (Remicade), and to compare this safety profile to that of UC subjects with similar disease severity treated with standard therapy. This primary objective also includes comparing the safety data of the subjects who discontinue infliximab treatment for any reason and restart treatment following a drug-free interval with the subjects who received infliximab without interruption.