We aimed to emphasize how useful PSMA PET/CT findings can be while trying to restage prostate cancer after radical prostatectomy in the presence of low prostate-specific antigen values. A 64-year-old man with pT3b N1 M0 Gleason 7 adenocarcinoma of the prostate presented 5 years postoperatively with a palpable axillary mass, whereas his prostate-specific antigen was 0.08 ng/mL. Conventional imaging studies and histopathologic findings of the axillary mass biopsy revealed inconclusive results. Ga-PSMA PET/CT demonstrated PSMA-positive metastatic lesions, the largest one being located in the right axilla. This finding confirmed metastatic poorly differentiated prostate cancer, and androgen deprivation therapy was initiated.