The importance of fungal organisms as allergens and pathogens has been increasing considerably over the last decade. This is due, on the one hand, to a general increase in the incidence of allergies, but also to the growing number of immunocompromized individuals such as AIDS patients or transplant recipients. This book summarizes what is currently known about the allergens of Candida, Aspergillus, Cladosporium, Alternaria, Coprinus, and Psilocybe, among others, and describes the application of recombinant allergens for diagnosis and new forms of therapy. The virulence factors and defense mechanisms against Aspergillus and Candida infections are discussed as are the various causes of superficial skin infections with fungi and the aerobiology of fungal spores and mycelia. A comprehensive chapter on fungal toxins and their importance for human and animal health is included, followed by a summary of the present state of fungal genome sequencing.