Numerous immunologic diagnostic modalities are available to the clinician investigating the etiology of occupational lung disorders. Certain tests--immunoassays for specific anti-IgE antibody, gel diffusion reactions, and immunoelectrophoretic techniques--may aid in the identification of specific antigens or analysis of antigens involved in the pathogenesis of environmental lung diseases. Other techniques--ANA assays, complement studies, and immune complex assays--should be regarded as complementary. For example, a specific non-histone nucleoprotein "marker," ANA has not been identified in any of the environmental fibrotic lung diseases, and ANA positivity does not always correlate with severity or progression of disease. Additionally complement assays and detection of circulating immune complexes do not identify specific antigens. Clearly, there are other assays useful in determining immunologic mechanisms that may be important in occupational lung diseases but were not discussed in this article. Bronchoalveolar lavage with cellular identification and therapeutically important when considering the activity of various lung disorders. Also, lymphokine and leukotriene identification, lymphocyte transformation studies, and assessment of macrophage function are contributing greatly to our understanding of the possible immunologic mechanisms involved in different environmental pulmonary diseases. Thus, the investigation of immunologic mechanisms offers an exciting and rewarding future in the evaluation of the pathologic mechanisms of occupational and environmental pulmonary disease.