Low molecular weight heparins (LMWHs) are widely used as clinical anticoagulant drugs. LMWHs are heterogeneous and highly negatively charged glycans prepared by chemical or enzymatic depolymerization of unfractionated heparin. The detailed structural analysis of a LMWH is essential for the drug quality control. In this study, a LMWH, enoxaparin sodium (a generic version of Lovenox) was separated to different molecular weights fractions by a Superdex peptide column. The disaccharide compositions, 3-O-sulfo group containing tetrasaccharides composition, and antithrombin III binding affinity of the fractions from this LMWH were analyzed.