Stachybotrys was found to be associated with idiopathic pulmonary hemorrhage in infants in Cleveland, Ohio. Since that time, considerable effort has been put into finding the toxic components responsible for the disease. The name Stachybotrys chartarum has been applied to most of these isolates, but inconsistent toxicity results arid taxonomic confusion prompted the present study. In this study, 122 Stachybotrys isolates, mainly from,water-damaged buildings, were characterized arid identified by combining three different approaches: morphology. colony characteristics, arid metabolite production. Two different Stachybotrys taxa, S. chartarum and one undescribed species, were found in water-damaged buildings regardless of whether the buildings were in Denmark, Finland, or the USA. Furthermore, two chemotypes could be distinguished in S. chartarum One chemotype produced atranomes, whereas the other was a Macrocyclic trichothecene-producer. The second undescribed taxon produced atranones and could be differentiated from S. chartarum by its growth characteristics arid pigment production. Our results correlate with different inflammatory and toxicological properties reported for these same isolates and show that the three taxa/chemotypes should be treated separately. The co-occurrence of these three taxa/chemotypes in water-damaged buildings explains the inconsistent results in the literature concerning toxicity of Stachybotrys isolated from that environment.