Biofilm, as a form of microbial existence, is very important from the medical point of view. Both our native microflora and pathogenic bacteria live in the biofilm form. Microbes growing in the biofilm show higher resistance to externall conditions and to the action of antimicrobials, which is considered to be very important virulence factor common to all biofilm-positive bacteria. The article deals with both biofilmformed native microflora and biofilm infections. and Veronika Holá.