Cyclosporin is a potent immunosuppressant, which has gained recent interest as a possible treatment for Crohn's disease. Chronic nephrotoxicity, however, has recently been demonstrated as a result of early treatment with high initial cyclosporin doses. We report the effect of a 3-month treatment with low-dose cyclosporin (5–7.5 mg kg−1 day−1) in 11 chronically active, therapy-resistant Crohn's disease patients. Eight of the 11 patients (72%) improved according to a clinical grading score and the Dutch Activity Index whereas 9/11 (82%) improved according to the Crohn's Disease Activity Index (P < 0.05) after 1 month. Three patients were withdrawn despite clinical improvement. One developed arterial hypertension, one dropped out and one required surgical treatment due to a small bowel stricture. Five patients (45%) completed the treatment period with improved clinical scores. After tapering-off, two patients (18%) were better at follow-up. No serious side-effects were encountered and it is concluded that low-dose cyclosporin treatment should be further investigated in Crohn's disease.