The mycobiota of indoor environments contains about 100-150 species and this is only a fraction of the more than 100,000 species of described fungi (Samson et al.2010,Miller 2011). Most species belong to the so-called anamorphic fungi which have been known as Deuteromycetes, Hyphomycetes or Fungi Imperfecti. They can produce high concentrations of spores and compounds which can affect our health. In addition to these micro fungi, a number of Basidiomycetes can be found indoors, growing on wood in buildings and are considered important degraders of wooden buildings material (see also Chapter 6 , 16 and 17 ).