OBJECTIVE To examine the pattern of immunoglobulins and cellular constituents in bronchoalveolar lavage fluid obtained from patients with sulfur mustard gas-induced asthma or chronic bronchitis as compared with healthy control subjects. METHODS We studied two groups of nonsmoking veterans with either bronchial asthma (n = 21) or chronic bronchitis (n = 28) believed to have been caused by sulfur mustard gas exposure and a third group of healthy, nonsmoking, non-sulfur mustard gas exposed controls (n = 17). Bronchoalveolar lavage was performed in all three groups. The cellular constituents, albumin content, and immunoglobulin concentrations were determined. RESULTS The three groups did not differ in age or in the serum albumin and immunoglobulin concentrations. The volume of bronchoalveolar lavage fluid recovered was approximately 10% less in the patients with asthma and chronic bronchitis (P = 0.008). The proportions of lymphocytes among the bronchoalveolar lavage cells were similar in all three groups, whereas the proportion of eosinophils was greater in lavage fluid from the asthmatic subjects than in either the healthy control subjects or the patients with chronic bronchitis (P = 0.0001). Both the total number of the recovered cells per milliliter of lavage fluid and the proportion of neutrophils were significantly greater in bronchoalveolar lavage from patients with chronic bronchitis than in healthy subjects or in the patients with asthma (all P <0.001). CONCLUSIONS The bronchoalveolar lavage cellular constituents of patients with sulfur mustard gas-induced asthma and chronic bronchitis are similar to those that have been observed previously in patients with asthma and chronic bronchitis from other common causes.