Polyamidoamine dendrimers were modified chemically by reaction with DOTA and DTPA type bifunctional metal chelators and were coupled to monoclonal antibody 2E4 without loss of protein immunoreactivity. Both the DTPA- and DOTA-dendrimer-antibody constructs were easily labeled with Y-90, In-111, Bi-212 or cold Gd(III) suggesting use of this dendrimer-macrocycle for mAb guided radiotherapy or imaging.