Aspergillus is a ubiquitous fungus which can penetrate into the human body in a natural way, by the respiratory tract or traumatically or iatrogenically. The presence of Aspergillus in the atmosphere is constant, in the environment, especially in moist places or in the neighbourhood of man, in dust. Aspergillus can colonise different substrates, the organic rests, soil, plants, cloting, climatisation, furniture. Aspergillus is in the first phase among the agents responsible for respiratory infections, for different physiopathological mechanisms and for some nosocomial infections. The author gives a review of sources of Aspergillus, especially for hospitalized patients, of mechanisms of the host’s defence, of factors enabling the survival of Aspergillus in hosts and of clinical picture. The prevalence of deep forms: aspergillome, allergic bronchopulmonal aspergillosis remain constant. New clinical forms appear due to modern therapy (immunosuppression, organ transplantation). The author describes further laboratory diagnostics with the interpretation of results and epidemiological studies. The early diagnostics of different types of aspergillosis, preventive methods and actual antimycotic therapy can inhibit the progress and improve the prognosis of these infectious diseases.

        Key words: aspegillus – aspergillosis.