Abstract: The characteristics of selective nonadsorptive of proteins on Ion Exchange Chromatography were described. (1) The retention of proteins on the organo zirconium phosphate column increases with the pI of the protein and decreases with increasing mobile phase pH and ionic strength(fig. 1). Rnase is more strongly retained at lower pH(fig. 2). (2) The retention maps of proteins(Fig. 3). Indicate that greatest retention on cation exchange column occurs when pH below the isoelectric point (pI), where the protein has a net positive charge whereas the largest retention on anion exchange column accurs pH above the isoelectric point where protein are negatively charge. For example, OVA with a pI of 4.6 would be retained on cation exchange column below pH 4.6 and on an anion exchange column above pH 4.6. (3) Chromatographic retention is plotted as a function of pH on both anion and cation exchange column(Fig. 3). OVA, Myo and Cytc can be retained anion exchange column even when pI=pH. The net charge retention model suggests that proteins showed not be retained on ion exchange column at their pI. This is not the case with many proteins. This behavior relates with charge distribution, charge density and their dimensional structure of proteins and matrix effects etc.