The present invention relates to a heparin derivatives having an average molecular weight of from about 4.6 to about 6.9 kDa and an anti-factor Xa activity of less than about 10 IU/mg and processes for their formation comprsing the steps of oxidation of unfractionated heparin, depolymerisation and reduction of resulting terminal groups.本發明係關於具有約4.6kDa至約6.9kDa之平均分子量及小於約10IU/mg之抗因子Xa活性的肝素衍生物及其形成方法,該等方法包含以下步驟:氧化未分化肝素、解聚合及還原所得末端基團。