In a previous report we published the immediate results of a 3-month placebo-controlled trial (n = 34) showing that cyclosporin (n = 37) has a beneficial therapeutic effect in active chronic Crohn's disease. Here we report on the final outcome of the patients. During the 3-month tapering-off period eight initially improved patients (36%) in the cyclosporin group worsened, as did six (55%) in the placebo group. The therapeutic gain of cyclosporin treatment was consistently significant during this period. It ranged from 22% to 25% (95% confidence limits, 2-46%). An outcome ranking showed that 7 patients of the cyclosporin group (19%) were substantially improved, 7 (19%) moderately improved, and 23 (62%) not improved after the tapering off. In contrast, no significant differences were seen during the 6-month follow-up period. Four patients of the cyclosporin group (11%) were substantially improved, 3 (8%) moderately improved, and 30 (81%) not improved at final follow-up. Significant interactions between cyclosporin and prednisolone treatment were demonstrated both at the end of the initial treatment period and at the end of the tapering-off period. We conclude that a short course of cyclosporin treatment does not result in long-term improvement in active chronic Crohn's disease.