Cyclosporin (CsA) has been proposed in the management of patients with acute ulcerative colitis (UC) in whom standard therapy failed and who were candidates for colectomy. Seven academic hospitals contributed to this retrospective study that included 29 patients (median age: 33 y. (15-74 y.); 12 females and 17 males). The median duration of the disease was 4 y. (0.3 to 33 y.). Before initiating CsA, patients were unresponsive to treatment including i.v. corticosteroids (n = 29), 5-ASA or salazopyrine (n = 19), azathioprine (n = 3), antibiotics (n = 14). The i.v. mean dose was 4 mg/kg/day and was adapted to blood level. Concomitant treatment included corticosteroids (n = 27). The median duration of i.v. CsA administration was 10 days (4 to 41 days). At the end of CsA administration, a global improvement was described in 20 patients while a surgery had to be performed immediately in 8 patients because of exacerbation of symptoms (n = 7) or perforation (n = 1). One other patient (74 y.) died because of Pneumocystis carinii infection. For the responders, maintenance therapy included: tapering dose of steroids (n = 12), azathioprine (n = 12), 5-ASA or salazopyrine (n = 10), methotrexate (n = 1) or oral CsA (n = II). The median duration of follow-up was 12 months (4 to 48 months). Among the 20 responders, 7 were subsequently referred for colectomy either electively (n = 3) or because of recurrence of the disease (n = 4). Among the 12 patients treated by azathioprine as a maintenance therapy, only 3 had to be referred for surgery (25%). Among the 8 patients who did not receive azathioprine, 4 were subsequently referred for a colectomy (50%) (NS). In patients with acute refractory UC who received CsA, the short-term efficacy (avoidance of immediate colectomy) was obtained in 20 out of 29 patients (69%). However, after a median follow-up of 12 months, only 13 patients were colectomy free (45%).