The synthesis of dextran radiocontrast carriers was undertaken to obtain derivatives expected to have slow and controlled biodegradation as well as slow extravascular diffusion features. The results presented here particularly concern derivatives including a methylamide spacer, prepared by condensation of the amine function of the contrast product with carboxymethylated dextran (CMD). The effect of various coupling reagents on the final yields is discussed. Concerning the macromol. features, all the synthesized products were characterized by acid-base titration, elemental anal., flame photometry, spectroscopic determinations and gel-permeation chromatog. GPC showed that the carboxymethylation of dextran leads to some reticulation (doubling the mol. weights), whereas the coupling of CMD with the contrast compound does not alter the mol. weight and the polydispersity index of the products appreciably.