A radioimmunoconjugate consisting of capromab linked to lutetium Lu 177 via the bifunctional macrocyclic chelator methoxy-tetraazacyclododecane-tetraacetic acid (MeO-DOTA) with potential antineoplastic activity. Lutetium Lu 177-capromab binds to human prostate specific membrane antigen (PSMA) expressed on tumor cell surfaces via its capromab moiety and, upon internalization, delivers cytotoxic beta radiation directly to PSMA-expressing tumor cells. PSMA is a cell surface glycoprotein abundantly expressed by prostate epithelium and is typically overexpressed by prostate cancer cells.