Environmental impactFungi and their toxic metabolites have been indicated as one of the possible causes of the Sick Building Syndrome (SBS), an illness associated with poor indoor air quality. This is the first study where mouldy environments were simultaneously monitored for the presence of 20 mycotoxins, volatile organic compounds and fungi. Substantial efforts were devoted to the establishment of optimal sample collection procedures including different techniques and fungal identification protocols. In more than 60% of the samples, one or more mycotoxins were found and related to fungal growth. Thus, mycotoxin production may be a possible risk factor for human health in water-damaged houses, especially for those mycotoxins with a higher incidence in air and dust. These findings contribute to a better understanding of the SBS.