On the surface of six different types of sterile plaster specimens placed in Petri dishes germs of strains Alternaria sp. (1 strain), Aspergillus (A.) versicolor (1stra- in), Stachybotrys chartarum (1), aspergilli of group A. niger (2), Cladosporium cladosporioides (1), Fusarium sp. (1), and Pencillium sp. (2) were inoculated in amounts from 10 4 to 10 7 colonies forming colonies. Within short time intervals the plasters were twice saturated with 1 ml sterile aqueous solution with peptone and glucose. Under experimental conditions the re-isolation from the surface of the plaster proved possible after 3-month incubation at 25 °C in a damp enviroment only in A. versicolor and strain Penicillium sp. D1, which was originally isolated from a wall in a flat. After three months incubation the surface of the plaster was secondarily contaminated in particular with penicillia and aspergilli group A. niger, rarely A. flavus, Acremonium sp. and Cladosporium sp. Re-isolation did not prove possible in strains Alternaria sp., aspergilli of group A. niger, Cladosporium cladosporioi- des, Fusarium sp., P. expansum and Stachybotrys chartarum.

        Key words: microscopic filamentous fungi - mycotic contamination of plasters