Abstract : Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system characterized by demyelination, neurodegeneration, and progressive disability. Increasing evidence suggests that the gut microbiota plays an important role in immune regulation. Through the microbiota-gut-brain axis, intestinal microorganisms may influence inflammatory processes and immune balance in patients with MS. This review aims to provide a synopsis of the current knowledge on the alterations of the gut microbiota in MS, highlighting its functional impact on immune and neurodegenerative processes. A comprehensive review of peer-reviewed studies indexed in PubMed, Scopus, and Web of Science was performed. Articles published between 2011 and 2025 examining gut microbiota composition and the microbiota-gut-brain axis in MS were included. Both early studies based on 16S rRNA sequencing and more recent large-scale metagenomic analyses were considered. Across multiple studies, patients with MS demonstrate reduced microbial diversity, depletion of short-chain fatty acid-producing bacteria, and enrichment of taxa such as Akkermansia and Methanobrevibacter. Alterations have also been reported in Blautia and Dorea, together with a consistent reduction in Prevotella. These microbial changes have been associated with impaired intestinal barrier function, systemic immune activation, and increased Th17-mediated inflammation. Gut dysbiosis may contribute to neuroinflammation and disease progression in MS. While current findings are promising, heterogeneity across studies highlights the need for future, large cohort studies.