肝素首先从肝脏发现而得名，由葡萄糖胺，L-艾杜糖醛苷、N-乙酰葡萄糖胺和D-葡萄糖醛酸交替组成的黏多糖硫酸脂，平均分子量为15KD，呈强酸性。它也存在于肺、血管壁、肠粘膜等组织中，是动物体内一种天然抗凝血物质。天然存在于肥大细胞，现在主要从牛肺或猪小肠黏膜提取。作为一种抗凝剂，是由二种多糖交替连接而成的多聚体，在体内外都有抗凝血作用。临床上主要用于血栓栓塞性疾病、心肌梗死、心血管手术、心脏导管检查、体外循环、血液透析等。随着药理学及临床医学的进展，肝素的应用不断扩大。
Heparin was first discovered in the liver and was named mucopolysaccharide sulfate, which was composed of glucosamine, L-iduronide, N-acetylglucosamine and D-glucuronic acid alternately. The average molecular weight of heparin sulfate was 15KD and it was strongly acidic. It also exists in lung, blood vessel wall, intestinal mucosa and other tissues, and is a natural anticoagulant substance in animals. Naturally occurring in mast cells, it is mainly extracted from bovine lung or small intestinal mucosa of pigs. As an anticoagulant, it is a polymer which is composed of two kinds of polysaccharides alternately linked. It has anticoagulant effect both in vivo and in vitro. It is mainly used in thromboembolic diseases, myocardial infarction, cardiovascular surgery, cardiac catheterization, cardiopulmonary bypass, hemodialysis and so on. With the development of pharmacology and clinical medicine, the application of heparin is expanding.