The present invention relates to a chemically modified glycosaminoglycan with an antifactor II activity of less than 10 IU/mg, an antifactor Xa activity of less than 10 IU/mg and an average molecular weight (Mw, weight average) from about 4.6 to 6.9 kDa. Also disclosed is a method of preparing the modified glycosaminoglycan and its medical uses.