After the inoculation in the head region of sphagnum moss vegetation (Sph. magellancium-Erica Association and Sph. apiculatum-Eriophorum angustifolium Ass.) reach the mycobacteria the hyaline cells of Sphagnum (Fig. 1). The count of M. intracellulare serotyp Davis decreases rapidly already in three days after the inoculation of Sph. magellanicum Ass. and this trend in the course of incubation is being continued. In 27 days following the inoculation only 2 of 7 specimens contained a small amount of this mycobacteria (Tab. 2, Fig. 2). In the head region of Sph. apiculatum Ass. the mycobacterial count was more rapidly going down. Already 13 days after the inoculation only 2 of 7 specimens were found mycobacteria-positive; 24 days after the inoculation no mycobacteria were present (Tab. 3, Fig. 3). The elimination of M. avium from the head region of Sph. magellanicum Ass. follows within 13 days after the inoculation (Tab. 4, Fig. 4). For the microbial growth well predisponated hyaline cells with their porous cell wall and hollow spaces possess probably a mechanism, which is effective against microbial contamination of the productive head region of Sphagnum vegetation. Our further investigations have shown, that the growth of mycobacteria follows in the deeper, partially decomposed region of Sphagnum vegetation (KAZDA, 1978).