The uveal tract, although comprising three anatomic sections such as the iris, the ciliary body and the choroid, may be regarded as a single functional unit, and is easily affected by several pathogenic agents that may act on either infectious, toxic and immune basis. Since such inflammatory stimuli do not usually locate primarily in the eye but rather elsewhere in the body, uveitis is often associated with systemic diseases. The Authors deal with several diseases frequently associated with anterior or posterior uveal inflammation, such as Behçet's disease, Vogt-Koyanagi-Harada's syndrome, Reiter's syndrome, juvenile rheumatoid arthritis, ankylosing spondylitis, sarcoidosis, Sjogren's syndrome, ulcerative colitis, psoriasis, tuberculosis and syphilis.