A radioimmunoconjugate consisting of the chimeric monoclonal antibody cG250 linked to the low energy beta-emitting radioisotope Lutetium 177, via the bifunctional macrocyclic chelating agent tetra-azacyclododecanetetra-acetic acid (DOTA), with potential antineoplastic activity. The antibody moiety of lutetium Lu-177 girentuximab binds to renal cell carcinoma (RCC) cells expressing the RCC-associated antigen G250; a cytotoxic dose of beta radiation is selectively delivered to G250-expressing RCC cells upon internalization of the radioimmunoconjugate.