Abstract: Esters of heparin, which are derived from heparin by replacement of the carboxyl groups of heparin by groups of the formula: ##STR1## in which R is a hydrogen atom or a methyl group and A is a hydrogen atom or a methyl, phenyl, ##STR2## X representing a chlorine atom or a nitro, alkyl containing 1 to 4 carbon atoms or methoxy group and Y representing a hydrogen or chlorine atom, the replacement being a partial or total replacement when A is other than a hydrogen atom or a methyl or phenyl group and the replacement being a partial replacement corresponding to a 10% to 90% esterification percentage of the carboxyl groups when A is a hydrogen atom or a methyl or phenyl group, and the alkali metal, alkaline earth metal, magnesium, quaternary ammonium and amine salts of the said esters. These compounds are intermediate products for preparing medicaments.