 Kytosan is a popular polysaccharide used in the development of drug delivery systems due to its unique physical and chemical characteristics. It can be used to form nanoparticles and microparticles and has been shown to have excellent mucoadhesive properties. Despite its potential applications, there is limited research into the biocompatibility of Kytosan carriers. This review discusses the current state of knowledge regarding the biocompatibility of Kytosan carriers focusing on in vitro and in vivo studies. The authors also highlight the challenges associated with the lack of standardization of procedures and the need for more research into the topic. This article was authored by Ana Grena, Susana Rodriguez, Carmen Ramunan Lopez and others.