Proteoglycans, produced by most eukaryotic cells are versatile components of pericellular and extracellular matrix. They are composed of protein core to which one or more glycosamino-glycan (GAG) chains are attached. One of few families of proteoglycans are glypicans. All glypicans share similar features as core protein of 60 kDa, 14 conserved cysteine residues, a special region localized near the plasma membrane, containing 2 or more Ser-Gly sequences for GAG attachment, hydrophobic C- and N-terminal parts of core protein similar to signal peptide, as well as linkage with external leaflet of the plasma membrane via a glycosylpho-sphatidylinositol. The glypicans are implicated in cell division, adhesion, migration and modulation of growth factor activities. Mutation in glypicans may cause few congenital diseases and premature death.