Method of separating proteins by ion exchange

A method of separating proteins from solution, comprising putting a solution of proteins into contact with an ion exchange resin, comprising a porous inorganic carrier with a particle size from 4 .mu.m to 5 mm, a specific surface area of approximately 5 to 150 m.sup.2 /g, a pore diameter of 500 to 2500 A and a pore volume of 0.4 to 2 ml/g, coated with less than 15 mg/m.sup.2 of a film of cross-linked polymer, containing or carrying either tertiary amines or quaternary ammonium salts, as anion exchanging groups, or acid functions as cationic exchanging groups, wherein at least one protein becoming fixed onto the ion exchange resin, and eluting the fixed protein(s) from the ion exchange resin.