Pilot studies with cyclosporin A (CsA, Sandimmun) in more than 100 patients with Crohn's disease have shown that CsA was more efficient in chronic active disease than in acute attacks. The onset of effect was rapid, usually within the first month, but most patients relapsed during the weeks following the interruption of CsA treatment. These findings were confirmed by a placebo-controlled study (parallel groups) in 71 patients, in whom the rate of improvement at 3 months was 61% on CsA and 33% on placebo. Promising results have also been reported after short-term use of intravenous CsA in severe acute ulcerative colitis. Further controlled trials are still ongoing in order to ascertain the efficacy of CsA administered according to the current safety guidelines (dose less than or equal to 5 mg/kg/day) for a period of one year in patients with chronic active Crohn's disease.