Enoxaparin sodium, a low-molecular-weight heparin (LMWH) prepared from porcine intestinal heparin, is widely used for the prevention and treatment of venous thromboembolism. The antithrombotic activity of heparin is mediated mainly through its activation of antithrombin (AT) and subsequent inhibition of coagulation factors. Heparin is a complex heteropolymer and the sulfation pattern of its alternating uronic acid and glucosamine sugar units is a major factor influencing its biological activity. The manufacturing process itself is associated with the introduction of exogenous microheterogeneities that may further affect its biological efficacy. This is important since enoxaparin is prepared by depolymerizing the heparin with the aim of optimizing its biological activity and safety. Changes during its manufacture could thus affect its biological activity and safety. The current study was performed to assess potential differences between the originator enoxaparin and a new generic enoxaparin commercialized by Teva. Heparinase digestion, AT affinity chromatography, gel permeation chromatography, anion exchange chromatography, and nuclear magnetic resonance methodologies were used. The results indicated differences in oligosaccharides related to the cleavage selectivity around the heparin AT-binding sequences of the Teva Enoxaparin Sodium Injection, USP and the originator Sanofi enoxaparin. These differences influence the strength of the AT-binding affinity of the individual oligosaccharides, their ability to activate AT and, therefore, the inhibitory potency on the proteases of the coagulation cascade. This study, together with other published analytical reports, describes specific compositional differences between generics and originator LWMHs. However, it is yet to be established whether such variations might have any clinical relevance.