AbstractAntibodies labelled with radioisotopes via chelating agents are being used increasingly for in vivo localisation or radiotherapy of tumours. The most widely used chelating agent is DTPA. Here, we describe technical modifications of the standard DTPA cyclic anhydride conjugation procedure and determine the in vitro stability of the DTPA‐antibody conjugates. The use of this derivative of DTPA combined with the use of appropriate buffers and small disposable gel filtration columns resulted in the development of a simpler and more rapid technique for the production of DTPA‐conjugated antibod