As part of a case-control study on the relation between home dampness and respiratory symptoms of children, house-dust samples were collected from bedroom floors and mattresses in 60 homes in The Netherlands. The house-dust samples were analyzed for the presence of fungal propagules by plating 30 mg of dust directly onto DG18 agar. A checklist and questionnaire were used to obtain information on the home characteristics and occupant behavior that may have an effect on the presence of fungal propagules in house dust. The geometric mean (GM) numbers of colony-forming units (CFU)/g dust collected from the floors was 8990. The number of CFU/g dust was significantly higher in dust from carpeted floors than in dust from smooth floors (GM, respectively, 12,880 CFU/g dust and 3530 CFU/g dust). The GM number of CFU/g dust collected from mattresses was 6760. Overall, the mean numbers of CFU/g dust collected from floors and mattresses were higher in bedrooms where damp spots mold growth, or both were observed. However, these differences were not statistically significant. The relation between home characteristics and the number of CFU/g dust of the most frequently isolated mold species (n = 17), including Alternaria alternata, Cladosporium cladosporioides, Penicillium brevicompactum, and Scopulariopsis brevicaulis, was also investigated. Only the type of flooring had a significant and consistent effect on the number of CFU/g floor dust of the different mold species.(ABSTRACT TRUNCATED AT 250 WORDS)