Investigations have been performed in a number of indoor environments where symptoms had been reported. The environmental measures comprised airborne endotoxin and (1 3)-b-D-glucan, and the effects were evaluated using a modification of the organic dust questionnaire and measurements of airway responsiveness. Level of (1 3)-b-D-glucan were around 1 ng/m3 when no symptoms were reported. Levels above 20 ng/mg3 were always associated with extended symptoms. Endotoxin levels were low and below those predicted to cause airways inflammation, caused by the (1 3)-b-D-glucan exposure or by other mold components for which (1 3)-b-D-glucan is a marker. The term "sick building" syndrome should be abolished and the symptoms observed be related to the relevant disease entities.