Thirty-seven workers exposed to formaldehyde (F) were evaluated to determine whether any of their respiratory or ocular symptoms were mediated by an immunologic response to F. Because there has never been a case of defined immunologically mediated respiratory or ocular disease as a result of exposure to gaseous F, we used clinical and immunologic criteria developed for immunologic respiratory diseases that result from inhalational exposure to trimellitic anhydride. A clinical assessment included review of a medical summary of history, physical examination, chest x-ray films, and pulmonary function studies. Serologic assessment was made with an ELISA for IgE and IgG to F human serum albumin. The final evaluation for immunologically mediated disease was based on both the clinical and serologic assessments. None of the workers had IgE or IgG antibody to F-human serum albumin or an immunologically mediated respiratory or ocular disease caused by F; however, some of the workers appeared to experience irritant symptoms caused by workplace exposure to F or other irritant chemicals.