Abstract: Articular involvement was present in 43% (CI-1.9) of patients with BD in Iran. Inflammatory arthralgia with morning stiffness was seen in 22% (CI = 1.6); Oligoarthritis, the most characteristic form mainly involving the large joints, was present in 20% (CI = 1.1); and monoarthritis mainly in the knee joints in 11 % (CI = 1.5). All these manifestations are usually transient with a tendency to relapse, but not as often as mucocutaneous lesions. Rarely they have chronic and progressive course and erosions will develop. Treatment with analygesics or NSAIDs or steroids (as local infiltrations or short term systemic) may be used to relieve pain. In the majority of cases, immunomodulatory drugs such as Colchicine (1 to 2 mg/d), Sulphasalazine (2 to 3 g/d) or levamisole (150 mg/d, 1 to 3 days/week) will suffice to prevent the further attacks or reduce their frequencies. In the rare resistant forms Methotrexate (7.5 mg weekly) may be used. Other cytotoxic drugs or Cyclosporin are not justified due to their side effects. Interferon has only short term effect during its prescription. Ankylosing Spondylities 9AS) is another form of articular involvement in BD. Its prevalence was 1.9% (CI = 0.5) in our patients, i.e. 16 times greater than the general population of Iran. Like the primary form of AS, it has a progressive course and the treatment principles is the same NSAIDs are the cornerstone of the treatment, while Sulphasulazine and MTX are the preferred choice as disease modifying drugs.