The gastrin-releasing peptide receptor (GRPR) is highly expressed in prostate cancer (77%-100%). Numerous studies have confirmed that GRPR PET imaging has emerged as a significant molecular imaging modality in prostate cancer, particularly serving as a complementary tool to PSMA PET for addressing cases with negative or insufficient PSMA expression. It demonstrates substantial value in initial staging (especially in intermediate- and high-risk patients), detecting sites of biochemical recurrence, assessing metastatic lesions (notably in mCRPC), and guiding treatment decisions. 68Ga-G21 and 68Ga-G23 are two novel molecular probes targeting GRPR. This study aims to evaluate their biodistribution and diagnostic performance in prostate cancer and compare them with 68Ga-PSMA-11 PET imaging.