Mycotoxins derived from Aspergilli can be encountered both in domestic and occupational environments, and the exposure may lead to severe health hazards. Several Aspergillus species are associated with mycotoxin production: A. ochraceus with ochratoxin A, A. fumigatus with fumitremorgins, gliotoxin and verrucologen, A. versicolor with sterigmatocystin, and A. flavus and A. parasiticus with aflatoxins. Sterigmatocystin may also be produced by A. flavus, A. nidulans, A. rugulosus, and A. unguis. Exposure to mycotoxin may occur via enteric, inhalation or direct contact to skin and mucosa. Acute and chronic disorders, irritation, systemic reactions and even cancer may develop after the exposure to these toxins. Mycotoxins act as immunosuppressants which may be in association with an increased prevalence of repeated infections found among the inhabitants of buildings with moisture problems.