The emergence of multidrug-resistant pathogens that has caused a serious problem in hospitals worldwide, has intensified the search for novel drugs, in order to replace or to be used in complement with the existing antibiotics. In this connection much interest has been focused on a group of antimicrobial peptides, so-called bacteriocins. These antagonising peptides, which are gene-encoded in contrast to those made by multi-enzyme-complexes, share some common physico-chemical properties, such as being small, cationic, amphiphilic and often being membrane active. However, they differ greatly from each other in their primary sequence and exhibit an impressively large inhibitory spectrum which covers almost all bacterial genera, including many important pathogens and food-spoilage bacteria. Many of these peptides are produced by lactic acid bacteria, organisms which have been used by man from ancient time in diverse fermentation processes, to improve and / or prolong self-life of many food and feed produ cts. Numerous bacteriocins have been purified and characterised in great detail, both at biochemical and genetic levels. Still, novel bacteriocins with new properties are reported in an increasing number in recent years. In this review we will give a brief status quo of the present knowledge on bacteriocin research thus different aspects such as their diversity in nature, biochemical properties, modes of action, biosynthesis and genetics will be treated.