EN
This paper is a review of studies on the interaction between cationic, amphiphilic quaternary ammonium salts and biological and model membranes. It has been pointed out that the compounds studied induce changes in both passive and active membrane properties such as mechanical, transport liquid-crystalline and electrical . An attempt has been made to explain the observed effects on the basis of the molecular shape and hydrophobic matching concepts. Some practical implications of the observations and their interpretation have also been noted.