Severe colitis is a life-threatening complication of ulcerative colitis. Early recognition of the severity of the colitis and intensive treatment and monitoring have all contributed to improved outcome. Since their introduction in 1950s, corticosteroids are the first line therapy for severe active ulcerative colitis (UC). Several prognostic parameters (such as stools movement per day, C-reactive protein, increased amount of intestinal gas or small bowel dilation, hypoalbuminemia, fever etc) help the physician to quickly introduce cyclosporin or to refer the patient to the surgeon. This decision requires a careful evaluation of the patient and a medical /surgical team. Infliximab seems to be a promising drug but more controlled trial are needed.