Exposure to mycotoxins produced by toxigenic molds growing in damp indoor spaces has been difficult to assess. Monitoring methods limit the characterization of inhalation exposure of any bioaerosol, especially that of mycotoxins. Biomarkers promise better ability to determine mycotoxin exposures 1.) through direct measures of toxins and their products in human tissues, 2.) through immunochemical methods, and 3.) measures of effect through novel approaches,e.g., proteomics or genomics. This paper summarizes both the problems inherent in measuring exposures and some of the promising methods that could help to resolve the current impasse.