Method for protein display on the surface of a host cell, the method comprising: (a) introducing into a host cell at least one or more polynucleotides which encode a protein of interest to be displayed on the surface of said host cell, wherein the protein of interest comprises at least one Fc domain; (b) contacting the surface of said host cell with a first label, wherein said first label is biotin, a biotin derivative, or a biotin analogue and covalently bound to the surface of said host cell; (c) contacting the surface of said host cell of (b) with a second label, whereby the second label specifically and non-covalently binds to said first label and to said protein of interest encoded by said at least one or more polynucleotides, wherein the second label is a multimeric protein, which is or comprises one of protein A, protein L, protein G, protein A-G fusion, domains E, D, A, B of protein A, fused to avidin, streptavidin, neutravidin; (d) expressing said at least one or more polynucleotides in said host cell under conditions sufficient for secretion of said protein of interest encoded by the at least one or more polynucleotides; (e) contacting said host cells of step (d) with means for specifically detecting said protein of interest bound non-covalently by said second label and detecting host cells which display the protein of interest on their surface, wherein the means for specifically detecting said protein of interest is one of a polyclonal antibody, monoclonal antibody, scFv-Fc, scFv, (Fab')2, Fab, minibody, diabody, or VHH antibody; optionally coupled to a further label and wherein the further label is a fluorescent label or radioisotope. (a) introducing into a host cell at least one or more polynucleotides which encode a protein of interest to be displayed on the surface of said host cell, wherein the protein of interest comprises at least one Fc domain; (b) contacting the surface of said host cell with a first label, wherein said first label is biotin, a biotin derivative, or a biotin analogue and covalently bound to the surface of said host cell; (c) contacting the surface of said host cell of (b) with a second label, whereby the second label specifically and non-covalently binds to said first label and to said protein of interest encoded by said at least one or more polynucleotides, wherein the second label is a multimeric protein, which is or comprises one of protein A, protein L, protein G, protein A-G fusion, domains E, D, A, B of protein A, fused to avidin, streptavidin, neutravidin; (d) expressing said at least one or more polynucleotides in said host cell under conditions sufficient for secretion of said protein of interest encoded by the at least one or more polynucleotides; (e) contacting said host cells of step (d) with means for specifically detecting said protein of interest bound non-covalently by said second label and detecting host cells which display the protein of interest on their surface, wherein the means for specifically detecting said protein of interest is one of a polyclonal antibody, monoclonal antibody, scFv-Fc, scFv, (Fab')2, Fab, minibody, diabody, or VHH antibody; optionally coupled to a further label and wherein the further label is a fluorescent label or radioisotope.