Quorum sensing is a communication system based on the actions of chemical signal molecules depending on the density of the cell population. These molecules are widely considered as effectors of the gene expression of several virulence factors. As a result, it has attracted a lot of attention because of its possible applicability as a target for treating infections. This review attempts to give a description of this system on gram negative bacteria specifically on Acinetobacter baumannii as an important nosocomial pathogen. Additionally, quorum sensing in biofilm will be also treated because it is considered as the origin of several chronic infections. Numerous studies have been carried out to prove the role of inhibitors in the disruption of quorum sensing, known as quorum quenching. Quorum quenching is a new strategy to eradicate bacterial infections due to the crucial intervention of quorum sensing in different virulence factors and particularly in the biofilm formation.