Ga-PSMA is a promising tracer for both primary staging and detection of biochemical recurrence in prostate cancer. PSMA is also expressed in the neovascular endothelium of various solid malignancies possibly due to tumor-associated angiogenic factors and endothelial cell sprouting. We report a case of a 73-year-old man of prostate cancer with rising prostate-specific antigen levels. Ga-PSMA PET/CT was performed, which showed a focal lung lesion, with subsequent histological confirmation of adenocarcinoma of the lung. Incidental lung lesions on Ga-PSMA in prostate cancer patients should elicit a differential of primary lung malignancy, especially if clinical and morphological suspicion is high.