Prostate-specific membrane antigen (PSMA) is a type II transmembrane protein, which is anchored in the cell membrane of prostate epithelial cells. It is highly expressed on prostate epithelial cells and strongly up-regulated in prostate cancer. Although, 177Lu-PSMA has been recently introduced for radionuclide therapy of metastatic castration-resistant prostate cancer (mCRPC) with continuously increasing interest and use worldwide. This guideline is intended to assist nuclear medicine physicians in evaluating and managing patients with mRCPC for whom radioligand therapy (RLT) using 177Lu-PSMA is a promising treatment option. In addition, more information could be provided by subsequent investigative studies in the field of RLT.