The removal of divalent metal ions including Cu(II), Co(II), Ni(II), and Zn(II) from aqueous solutions by membrane filtration was studied with the help of water-soluble chitosan. The Amicon regenerated cellulose YM10 and YM30 were used as ultrafilters. Experiments were performed as a function of aqueous pH, the concentration ratio of chitosan to metals (beta), and applied pressure (Delta P). It was shown that at neutral condition the removal of Cu(II) was more efficient compared to other metals. Furthermore, metal removal from acidic solutions (pH < 6) could be enhanced by 6-10 times via the addition of chitosan. The effect of the presence of inorganic salts on the removal was also studied. Finally, the fouling phenomena during filtration was analyzed by conventional filtration theory considering compressible nature of the deposited gel.