Caenorhabditis elegans is an ideal model organism for studying glycoscience (Fig. 45.1). Because approximately 60–70% of its genes are orthologous to those in humans, many human disease models—both single gene and polygenic—have been introduced and widely studied [1]. With the advent of advanced imaging techniques, the development of C. elegans can be observed in detail in vivo, from germ cell formation to adulthood. The application of modern analytical methods in glycoscience research using C. elegans has continuously revealed new glycan functions (see the C. elegans GlycoGene Database) [2]. As a model organism that allows both forward and reverse genetics, C. elegans is used for the identification of related genes because of the ease of obtaining mutants and performing suppressor or enhancer screening. Over 13,000 gene knockout (KO) strains have already been obtained. The ability to freeze mutants and maintain lethal or infertile mutant strains as heterozygotes using fluorescent balancers is also a major advantage over other model organisms [3]. In addition to obtaining new mutants and inhibiting gene function(s) by RNAi, techniques for genome editing with CRISPR-Cas9, introducing genes of any size into the genome, and expressing genes in a temporally or spatially regulated manner using bipartite expression systems such as Gal4/UAS, QF (and QF2)/QUAS, tetR (and rtetR)/tetO, and LexA/lexO have been well established [4]. Biochemical analysis is also straightforward. Methods for extracting nearly all proteins from C. elegans covered with cuticles have been well established. In addition, a recently introduced technique called TurboID provides a means to isolate and identify proteins interacting with biotin-labeled proteins with high sensitivity and high yield [5]. Furthermore, the advent of the latest technologies—such as genome profiling analysis by bioinformatics, three-dimensional structure prediction using AlphaFold and related methods, and proteome analysis by the nanopore method—will dramatically increase the value of C. elegans for glycoscience studies. With these latest technologies, dramatic progress can be expected in the elucidation of glycogene functions, including those of human glycogenes.