Radiopharmaceuticals based on antibody biomolecules are widely used in oncology for positron emission tomography (PET). Trastuzumab, an antibody that targets the epidermal growth factor receptor 2 (HER2), has been extensively studied for both preclinical and clinical cancer imaging. This MIB guide specifically focuses on the radiolabeling of the antibody trastuzumab with zirconium-89 (Zr) and copper-64 (Cu) for PET imaging. The guide describes the steps for conjugating trastuzumab with p-SCN-Bn-deferoxamine (DFO) or 2,2',2''-(1,4,7-triazacyclononane-1,4,7-triyl)triacetic acid (p-SCN-Bn-NOTA) chelators through conjugation between the isothiocyanate (-SCN) functional group on the chelator with lysines on the trastuzumab. We also describe subsequent radiolabeling steps with Zr or Cu. The steps described here can be adapted to the radiolabeling of other antibodies upon protocol optimization.