Policy makers and insurance companies decide on coverage of care by both calculating (cost-) effectiveness and assessing the necessity of coverage.To investigate argumentations pertaining to necessity used in coverage decisions made by policy makers and insurance companies, as well as those argumentations used by patients, authors, the public and the media.This study is designed as a realist review, adhering to the RAMESES quality standards. Embase, Medline and Web of Science were searched and 98 articles were included that detailed necessity-based argumentations.We identified twenty necessity-based argumentation types. Seven are only used to argue in favour of coverage, five solely for arguing against coverage, and eight are used to argue both ways. A positive decision appears to be facilitated when patients or the public set the decision on the agenda. Moreover, half the argumentation types are only used by patients, authors, the public and the media, whereas the other half is also used by policy makers and insurance companies. The latter group is more accepted and used in more different countries.The majority of necessity-based argumentation types is used for either favouring or opposing coverage, and not for both. Patients, authors, the public and the media use a broader repertoire of argumentation types than policy makers and insurance companies.