A prostate-specific membrane antigen (PSMA)-targetingbioconjugate of H4pypa was synthesized and radiolabeled.The uptake of [201Tl]Tl-pypa-PSMA in DU145 PSMA-positiveand PSMA-negative prostate cancer cells was evaluated in vitro and showed evidence of bioreductive release of 201Tland cellular uptake characteristic of unchelated [201Tl]TlCl.SPECT/CT imaging was used to probe the in vivo biodistributionand stability of [201Tl]Tl-pypa-PSMA. This evidence concerns the gene FOLH1 and prostate carcinoma.