The retention capacity of alginate bends coated by two polycationic polymers, chitosan or diethylaminoethyl-dextran (DEAE-dextran) was studied. When beads were stored in water or in a 0.9% NaCl solution, the chitosan coating was stable for more than 5 months or less than 2 months, respectively. The greater the concentration of the polycationic polysaccharides in the formation solution of the beads, the lower the haemoglobin release. Haemoglobin release depended on the pH conditions of bead formation. With chitosan, the lowest release was observed at pH 5.4 (4.4% of released haemoglobin) and at pH 2 (1.5%), respectively, during bean formation and storage. With DEAE-dextran the lowest release was observed at pH 4 (10%).