We determined the relative frequencies of the different types of chronic uveitis, and the possible associated conditions, among 400 consecutive patients with chronic uveitis examined during the years 1982 through 1988. Of the 400 patients, 183 (45.75%) had anterior uveitis, 98 (24.5%) ahd panuveitis, 61 (15.3%) had intermediate uveitis, and 58 (14.5%) had isolated posterior uveitis. Only four of the 98 patients with panuveitis (4.1%) were considered idiopathic after a comprehensive examination, whereas 94 of the 183 patients with anterior uveitis (51.4%) were similarly classified. We found an associated condition in 242 of the 400 patients of the study group (60.5%). Of these 242 patients, 61 had Behçet's disease, which constituted the most frequently encountered associated condition in this study. Of the 61 patients with Behçet's disease, 58 had panuveitis and constituted 59.2% of the panuveitis group. Of the 61 patients with intermediate uveitis, 17 (27.9%) had a concurrent disease. An associated condition was found in 95% and 96.2% of patients with unilateral and bilateral panuveitis, respectively, but in none of the patients with unilateral intermediate uveitis. Environmental, cultural, or genetic factors may be accountable for the differences discovered between our findings and those of previously published studies from the United States and England with respect to relative frequencies of some of the associated diseases in patients with chronic uveitis.