Treatment of severe colitis in Behcet's syndrome with thalidomide (CG-217). A 35-year-old male patient, known in our department since 1979 on account of a severe and complete Behcet's syndrome, was treated with thalidomide (CG-217) as a final pharmacological measure to avoid colectomy during a severe attack of Behcet colitis. Prior to the administration of thalidomide, the patient had been treated for 7 weeks with full parenteral nutrition and high doses of steroids intravenously without a satisfactory effect on the colitis. Treatment with sulphasalazin was unsuccessful because of a decreasing number of platelets on this drug. After a few days on thalidomide, 300 mg given once daily at bedtime, the patient's stools were normalized and without reaction for blood, his oral ulcers and pleural effusion disappeared, and his steroid doses could be reduced. Gradually he was put on oral nutrition again, and his rectal mucosa became normalized. The dose of thalidomide was reduced to 200 mg, and then to 100 mg daily when the patient was discharged from hospital, less than 3 weeks after institution of the drug treatment. After 5 months as an out-patient his condition is still satisfactory and without symptoms of his former disease. Thalidomide has previously been reported to be of value in treatment of Behcet's syndrome, but to my knowledge never with such a dramatic effect on a severe colitis as reported in this case. 