Sarcoidosis is a granulomatous disease of unknown cause characterized by a lymphocytic alveolitis. Previous studies have shown that the inflammatory cell population of the distal lung units of patients with this disorder can be accurately assessed using bronchoalveolar lavage (BAL). The present study evaluated the uniformity of BAL between different sites of the lung in patients with sarcoidosis. In general, there was a good correlation between sites for percentages of lymphocytes (LYM) (r = 0.750, p less than 0.0001), LYM number (r = 0.356, p = 0.0007), percentages of neutrophils (NEUT) (r = 0.917, p less than 0.0001), NEUT number (r = 0.999, p less than 0.0001), and macrophage (MAC) number (r = 0.858, p less than 0.001). Despite the good overall correlation, we found that 43% of the patients with high percent LYM (greater than 30%) had this finding on one side only. These patients did not differ from the group as a whole based on radiographic stage of their disease but did differ in the number of radiographs demonstrating focal infiltrates (2 of 28 patients with both sides less than 30% LYM, 2 of 14 with both sides greater than 30% LYM, and 4 of 9 with only one side greater than 30% LYM p less than 0.05 by chi-square); and in each situation the highest percent LYM was seen on the side with focal changes on the chest radiograph.(ABSTRACT TRUNCATED AT 250 WORDS)