Microparticles of curdlan, synthesized through crosslinking with epichlorohydrin in organic suspension media, were chemically modified with the aim of introducing strongly and/or weakly acidic anionic and palmitoyl hydrophobic groups. Microparticles of both curdlan and curdlan derivatives were physico-chemically characterized. Study of the interaction with enzymes, such as lysozyme, and vaccines, such as tetanus anatoxin, showed a co-operative protein retention effect, induced by electrostatic and hydrophobic forces. The results of the in vitro release studies on support-protein complexes recommend them as potential controlled release systems.