This review focuses on the only polysaccharide compartment of the biomatrix of connective tissues: hyaluronan. This pure polysaccharide is present in the largest amount and highest concentration in three connective tissues of the adult vertebrate body: the vitreus of the eye, the synovial fluid of the joint, and the dermis of the rooster comb. The molecular properties, weight average molecular weight, polydispersity, and elastoviscous properties of hyaluronan, as well as its distribution in these biomatrices, are presented. The differences and similarities in the biological function of this polysaccharide in the biomatrix are discussed. The effect of aging on the hyaluronan content of the vitreus, synovial fluid, and the dermis of human skin is also presented.