The streaming potential measurements of a polyethylene microfiltration (PE-MF) membrane were carried out under aqueous solutions of five single salts (NaCl, KCl, MgCl2, Na2SO4 and MgSO4); the zeta potential and surface charge density of the membrane were estimated on the basis of the Helmholtz-Smoluchowski equation and the Gouy-Chapmann theory. The results show that the PE-MF membrane has a weak negative charge due to the specific sorption of ions, and behaves almost as a certain zeta potential in a very dilute salt solution and as almost a certain surface charge density in a solution with a concentration more than 4 mol(.)m(-3). However, the streaming potential, the zeta potential and the surface charge density of the membrane depend strongly on the salt concentration and the type and valence of ions.