Some patents of low-molecular-weight heparins (LMWHs) have expired and others are about to expire. Biosimilar versions of those drugs are available for clinical use in several countries. However, skepticism persists about the possibility of obtaining preparations similar to the original drug, because of the complexity of the process to generate LMWHs. In recent years, our laboratory has analyzed biosimilar samples of enoxaparin available for clinical use in Brazil (30 different batches and 70 finished products). Those preparations were assessed regarding their chemical structure, molecular weight distribution, in vitro anticoagulant activity, and pharmacological effects in animal models of thrombosis and bleeding. Our results have clearly shown that biosimilar preparations of enoxaparin are similar to the original drug. Our results have shown that those biosimilar versions of enoxaparin are a valid therapeutic alternative, which are, however, in need of appropriate regulation to ensure compliance with regulatory requirements.