Abstract: The invention relates to an amphiphilic heparin derivative formed from at least one type of partially N-desulfated heparin and at least one type of bile acid comprising one or several bile acid molecules grafted on a heparin molecule by an amide bond formed between the terminal carboxylic acid function of a bile acid and a primary heparin amine function which is initially present in the heparin or resulting from the N-desulfation. The inventive derivative is characterized in that the number of grafted bile acid molecules per 100 heparin disaccharide units ranges from 15 to 80 approximately.