Familial Mediterranean fever (FMF) is a monogenic autoinflammatory disease characterized by fever and serositis attacks caused by mutations in the MEditerranean FeVer (MEFV) gene encoding the pyrin gene. Gain of the function mutations of the pyrin gene lead to stimulation of pro-inflammatory cytokines. Persistent pro-inflammatory situation in the course of FMF may play a role in the development of some other inflammatory diseases such as Behcet's disease, psoriasis, and vasculitis. Multiple sclerosis (MS), as a demyelinating disorder, is also more commonly seen in FMF patients compared to the general population. There are scarcely any research reporting that these two diseases coexist in more than one person in the same family. We have discovered cases of FMF and demyelinating disorders in five members of two different families. Besides the two families we are reporting, there are only four other families reported so far. Having combined the data of all these six families, we present a case-based review in this study. We aimed to draw attention of physicians to familial co-occurence of FMF and demyelinating disorders and also to discuss possible mechanisms of the coexistence of these two diseases in light of the literature.