Glycoprotein biosynthesis describes the process of co- and posttranslational attachment of sugar chains to proteins, a process that has been found in nearly all known organisms. Human deficiencies evoked by mutations in the glycosylation pathway of glycoproteins lead to congenital disorders of glycosylation (CDG), a rapidly expanding group of autosomal recessive inherited metabolic diseases with multisystemic phenotypes that are mostly combined with severe neurological impairment. Although investigations on new types of CDG have proceeded rapidly in recent years, the correlation between inaccurate protein glycosylation and pathological loss of functionality of distinct organ systems remains widely unknown, and therapeutics for the patients are mostly not available. Therefore, mouse models provide an outstanding helpful tool for investigations on different aspects of glycosylation deficiencies that cannot be performed in patients or cell culture. This review focuses on existing mouse models generated for the types of CDG that affect the N-glycosylation pathway.