Acidic glycosphingolipids, gangliosides are highly and consistently expressed in nervous tissues of vertebrates at high levels. Therefore, they have been believed to be largely involved in the development and function of nervous systems. Recent studies with genetic engineering of glycosyltransferase genes have revealed novel aspects of roles of gangliosides in the regulation of nervous tissues with substantial basis. In this review, novel findings on the ganglioside functions and their modes of action elucidated mainly by studies of gene knockout mice have been summarized. In particular, roles of gangliosides in the regulation of lipid rafts to maintain the integrity of nervous systems have been reported with a focus on the roles in the regulation of neuro-inflammation and neurodegeneration via complement systems. In addition, recent advances in the studies of congenital neurodisorders due to the genetic mutaions of ganglioside synthase genes, and also in the techniques for the analysis of ganglioside functions have been introduced.