The aim of the present study was to assess the human dosimetry of the GRPR antagonist 68Ga-NODAGA-4-amino-1-carboxymethyl-piperidine-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 (NODAGA-MJ9) [16] in the first five patients with recurrent prostate cancer included in a dual-tracer positron emission tomography (PET) protocol. Here, GRPR is linked to prostate carcinoma.