The purpose of this review is to characterize the environmental microbiology, hospital epidemiology, diagnosis and treatment of nosocomial aspergillosis. Appropriate environmental control measures are important in preventing or arresting an outbreak of nosocomial aspergillosis. These include selective environmental microbiological surveillance and floor to ceiling barriers during construction or renovation. These is particularly important for the bone marrow transplant units and units with persistently granulocytopenic patients. We have summarized the point source and cited or formulated the environmental correction measures relating to 25 outbreaks of nosocomial aspergillosis involving a total of more than 100 patients. The most frequent settings of nosocomial invasive aspergillosis occurred in granulocytopenic patients following respiratory infection from an airborne source, associated with hospital construction or contaminated ventilation systems.