The clinical response to thalidomide in 30 male patients with Behçet's disease was reviewed. Twenty-six patients with orogenital ulcerations responded (20 completely and 6 partially). Cutaneous lesions including erythema nodosum or necrotic pseudofolliculitis were controlled by treatment in the majority of cases. All patients with arthritis responded (13 completely and 1 partially). Uveitis was improved in 3 patients, stabilizated in 4 and aggravated in 4. Patients with thalidomide purposely discontinued experienced a flare; the reintroduction of therapy controlled the flare. Side effects were uncommon and included skin rash and somnolence. These results suggest that thalidomide may be useful in the therapy of the various manifestations of Behçet's disease and that a controlled study is indicated.