Exposure to molds has become a significant health risk to an increasing number of workers in various occupations throughout the nations. Fungal antigens are able to cause occupational asthma, rhinoconjunctivitis, hypersensitivity pneumonitis and organic dust toxic syndrome (ODTS) for instance among farmers, construction workers, housekeeping personnel as well as factory and sawmill workers who have to handle moldy and contaminated materials. In recent years, an increasing incidence of mold-induced diseases has been encountered in moldy contaminated water-damaged buildings. This has occured both in homes and workplaces. Symptomatic persons occupying moisture problem buildings may develop asthma, rhinitis, ODTS and HP. However, the majority of the exposed individuals present with conjunctival, respiratory or systemic reactions the immune mechanisms of which remain unclear. In the present summary some aspects will be presented on health effects which appear among workers exposed especially to fungal antigens.