Abstract: The present invention is directed to a multimeric agent and a multimeric conjugate formed from this multimeric agent and a biologically active agent. Said multimeric conjugates have a longer life time in vivo and an increased avidity compared to the unmodified biologically agent. The present invention is further directed to a pharmaceutical or diagnostic composition containing said conjugate as well as to a method of its production. The invention additionally provides the use of said conjugates for the detection, determination, separation and/or isolation of a specific binding partner and for the diagnosis, prophylaxis and treatment of diseases in which the specific binding partner is directly or indirectly involved.