Twenty workers exposed to trimellitic anhydride (TMA) powder were evaluated to correlate respiratory symptoms with total antibody activity against trimellityl human serum albumin (TM-HSA). Further, specific IgG, IgA, and IgE against TM-HSA were compared to total specific antibody levels against that antigen. The workers were categorized clinically as having either the late respiratory systemic syndrome (LRSS), immediate rhinitis and asthma, or an irritant reaction. There were no histories compatible with the pulmonary disease--anemia syndrome. Total antibody and IgG antibody activity to TM-HSA correlated well (R8 = 0.75, p less than 0.05). Total antibody activity was found in almost all TMA-exposed workers, it did not discriminate the symptomatic workers from asymptomatic workers as well as did the IgG or total antibody determinations. IgE antibody activity against TM-HSA was elevated in one worker with immediate-type asthma. Previous studies correlated symptoms caused by TMA inhalation with antibody activity. This study indicates that clinical assessment plus total antibody determination or IgG antibody and IgE antibody determination should establish a means of diagnosis of the presence or absence of immunologic respiratory disease caused by TMA powder.