Disclosed is a method for purification of monoclonal antibodies or of a fusion protein between the Fc segment of an antibody and a second polypeptide, including a) an affinity chromatography step on a resin having as a matrix a crosslinked methacrylate polymer gel, on which the protein A is grafted, b) a viral inactivation step, c) a chromatography step exchanging cations on a resin having a crosslinked agarose gel matrix, on which sulfonate groups (—SO3—) are grafted using dextran-based spacer arms, d) a chromatography step exchanging anions on a hydrophilic membrane of polyethersulfone coated with a crosslinked polymer on which quaternary amine groups (Q) are grafted, and e) a nanofiltration step using a filter having an asymmetric polyethersulfone double membrane with a porosity of approximately 20 nm.