Efflux phenomenon induced by the presence of efflux pumps is one of the bacterial resistance mechanisms against active substances ofbiocides. Proteins and protein systems create efflux pumps, which are connected with the cell envelope structure ofbacteria. The efflux pump's function is transportation of active substances of disinfectants outside the bacterial cell. The biocides active substances rinsed out of bacterial cell by efflux were described for quaternary ammonium compounds, biguanides, phenols and diamidine. Bacterial resistance induced by efflux was not confirmed in the presence of such active substances like: alcohols, aldehydes, peroxides and chlorine compounds and their derivates. Bacterial resistance to active substance ofbiocides can be caused by two or more resistance mechanisms i.e. efflux mechanisms and reduce diffusion. The cooperation of resistance mechanisms to biocides can result difficulties in pathogenic bacteria eradication. The spread of these bacteria can be an epidemic threat.