In conjunction with the occurrence of medical complaints the author examined sewage sludge, the atmosphere of a research laboratory and atmosphere of a hou- sehold. As the agent causing medical problems the author identified microscopic thread fungi: Cephaliophora tropica endemic in tropic regions, the phytopatho- genic fungus Fusarium culmorumin a concentration of 3400 CFU. m -3 andcommon concentrations of a mixed population of fungi in an elderly patient with a diagno- sed allergy to fungi. The author discusses the importance of microscopic thread fungi in the environment.

        Key words: microscopic fungi - sewage sludge - atmosphere