Ulcerative colitis is a relapsing–remitting inflammatory disease affecting the colon and is associated with considerable morbidity. In acute severe attacks, there continues to be an associated mortality rate of 1–2%, even in specialist units. During an acute severe exacerbation, approximately two-thirds of patients will respond to intravenous corticosteroid therapy, the accepted first-line therapy in such cases. For steroid-refractory patients, options are limited to surgery (colectomy) or second-line agents, such as ciclosporin or infliximab, used in an attempt to salvage the colon. Considerable debate exists over the optimal management of such patients. During the last decade, an increased understanding of the pathogenesis of inflammatory bowel disease has led to the rapid development of other biological agents, such as basiliximab and visilizumab. Novel methods, such as leucopheresis, have been studied and other established immunomodulatory agents, such as tacrolimus, have also been suggested. The purpose of this review is to highlight some of the areas of recent development in the treatment of acute severe ulcerative colitis and review important safety data, with a particular emphasis on biological agents.