The present invention relates to novel stabilized IgG4 antibodies, to methods of producing such antibodies and to uses of such antibodies as a medicament. In a main aspect, the invention relates to a stabilized IgG4 antibody, comprising a heavy chain and a light chain, wherein said heavy chain comprises a human IgG4 constant region having a substitution of the Arg residue at position (409), the Phe residue at position (405) or the Lys residue at position (370).