Microorganisms like bacteria and molds produce a huge variety of substances, and a part of them are released into the environment. Some compounds like, e.g. alcohols or ketones are volatile, therefore found in the air and called MVOC. Those compounds were considered helpful to track especially hidden mold damage. The study presented here showed, that the emission pattern varies from genus to genus and sometimes even from fungal strain to fungal strain. The results concerning the emission rates from different infested building materials proved, that the concentrations produced are much too low to be detected in indoor air, especially considering the dilution because of ventilation. Therefore, we conclude that MVOC should not be used as predictors for mold damage in indoor environments.