Abbreviations Inflammatory Bowel Disease (IBD) Ulcerative Colitis (UC) The exact role of thiopurines, azathioprine and 6-mercaptopurine in ulcerative colitis (UC) regimens has been debated. In particular, their use in UC remains controversial because the evidence lies in small clinical trials. In this article, we briefly review the evidence on the therapeutic efficacy of thiopurine.