Behcet syndrome is a multisystem disorder that usually presents with recurrent oral and genital ulcers. Onefouh of patients develop superficial or deep vein thrombophlebitis. Iritis, uveitis, and nondeforming ahritis may also occur. The 50-year-old drug abuser also has a multisystem disease, including systemic complaints, hypeension, skin lesions, neuropathy, and an abnormal urine sediment. This complex suggests a vasculitis, paicularly polyaeritis nodosa. The disease is a necrotizing vasculitis of small and medium muscular aeries. The pathology of the kidney includes an aeritis and, in some cases, a glomerulitis. Nodular skin lesions show vasculitis on biopsy. The 19-year-old with low back pain, morning stiffness, and eye pain has complaints that suggest ankylosing spondylitis. This is an inflammatory disorder that affects the axial skeleton. It is an autoimmune disorder that has a close association with HLA-B27 histocompatibility antigen. Anterior uveitis is the most common extraaicular complaint. Aoic regurgitation occurs in a few percent of patients. The elderly male presents with nonspecific joint complaints typical of polymyalgia rheumatica. The high erythrocyte sedimentation rate is characteristic. The transient loss of vision suggests concomitant temporal aeritis, an impoant association seen paicularly.