A case of building-related health complaints was investigated with respect to the relationship among frequency of symptoms, antibodies to albumin conjugates of formaldehyde (HCHO), toluene diisocyanate (TDI), and tirmellitic anhydride (TMA), and volatile organic chemicals (VOCs). The indoor air concentrations of VOCs, HCHO, TDI, and TMA did not exceed Fed-OSHA and ACGIH permissible standards. However, HCHO concentrations ranged between 0.05 and 0.08 ppm. The reported symptoms were multiple, involving the eyes, nose, sinuses, throat, lungs, skeletomuscular system, and central nervous system. Anti-HCHO, -TDI, and -TMA isotypes were found in 12 of 14 full-time employees and were nondetectable in one part-time employee. There was a positive, but not statistically significant, correlation (r values ranged between .24 and .55) between symptoms and the geometric mean titers to conjugates. The data suggest that a synergistic immunological response to airborne chemicals may be occurring in these subjects. In conclusion, immunological monitoring of affected individuals where chemicals are suspected may prove to be useful in future investigations of building-related illness.