Secretion of extracellular vesicles (EVs) is a common feature pf both eukaryotic and prokaryotic cells. Isolated EVs have been shown to contain differetn types of molecules, including proteins and nucleic acids and reported to be key players in intercellular communication. Little is known of EVsecretion in fish and the effect of infection on EVs realise and content. In the present study, EVs were isolated from serum of healthy and Piscirickettsia salmonis infected Atlantic salmon in order to evalaute the effect of infection on EV secretion.