A study was undertaken in a number of rowhouses, some of which had had previous problems related to dampness and water leakage. The aim of the study was to assess the relation between exposure to airborne (1--> 3)-beta-D-glucan, a cell-wall substance in molds, and airways inflammation. The study involved 75 houses with indoor (1--> 3)-beta-D-glucan levels ranging from 0 to 19 ng/m3. Of 170 invited tenants, 129 (76%) participated in the study. A questionnaire relating to symptoms was used, and measurements were made of lung function and airway responsiveness. Myeloperoxidase (MPO), eosinophilic cationic protein (ECP), and C-reactive protein (CRP) were measured in serum. Atopy was determined with the Phadiatop test. The major findings were a relation between exposure to (1--> 3)- beta-D-glucan and an increased prevalence of atopy, a slightly increased amount of MPO, and a decrease in FEV1 over the number of years lived in the house. The results suggests the hypothesis that exposure to (1--> 3)-beta-D-glucan or molds indoors could be associated with signs of a non-specific inflammation.