Twenty-nine patients with Behçet's disease were studied. Of these, 17 patients were followed up for a mean duration of 37 months and 12 for a mean of 18 months. Male to female ratio was 3.1:1. Of the 29 patients, 26 were Arab, 2 Asian and 1 Black African. The prevalence in the country was 2.1:100,000 population, in Kuwaitis 1.58:100,000, in non-Kuwaiti Arabs, 2.9:100,000 and in non-Arabs, 1.35:100,000 population. The frequencies of the various manifestations were: oral ulcers, 100%; genital ulcers, 93%; skin manifestations, 76%; arthropathy and ocular disease, 69% each; psychiatric disorders, 38%; vascular complications and positive Pathergy test, 34% each; gastrointestinal symptoms, 21%; oesophageal and CNS involvement, 14% each; and peritonism, renal and pulmonary involvement, 7% each. Kuwaiti bedouins seemed to be resistant to the disease, probably due to environmental and/or dietary factors. The hot arid climate of the Gulf had no effect on the course of the disease once it had developed.