Following the rapid developments in genomics and proteomics in recent decades, the analysis of the associated sugars became a critical center of interest, particularly in the field of analytical chemistry. Indeed, their synthetic route, diversity and complexity make these carbohydrates, and in particular glycosaminoglycans (GAG), a real analytical puzzle. These polymers are involved in a wide range of biological processes through their particular interaction with proteins. This article aims to show the contribution of separation sciences to the identification and characterization of interaction sites on GAGs. After a brief review of the structure and diversity of GAGs, the question was: do GAGs have a specific interaction motif with proteins? A literature review showed that this question is still controversial and that the reality is more nuanced. This review presents the different separative strategies used to try to identify such a specific GAG binding site if there is one.