Dilatation of the colon in severe and fulminating ulcerative colitis is a sign of toxic megacolon and emergency surgery is usually the favored treatment option. Here we describe our experience with three cases of ulcerative colitis with megacolon in which surgery was avoided by treating the patients with a continuous intravenous infusion of cyclosporine, with full cooperation of the surgeons. We recommend that continuous intravenous infusion of cyclosporine be considered as an effective option for the conservative management of severe, fulminating ulcerative colitis with megacolon.