[en] Full text: Peptide receptor radionuclide therapy (PRRT))) using α-emitting radionuclides (e.g. ²¹³Bi) with high linear energy transfer (LET) may have therapeutic advantages over lower-LET emitters such as ⁹⁰Y and ¹¹¹In. We evaluated the ²¹³Bi-labelled somatostatin analogue DOTATOC. ²¹³Bi was obtained from an ²²⁵Ac generator. ²¹³Bi decay (t_1/2, 45.6 min) yields α-, β- and y-emissions. The ideal conditions for radiolabelling with regard to temperature, incubation time, pH and amount of DOTATOC were determined. Incorporation yield (≥ 99.9%) and radiochemical purity (≥95%) were determined by ITLC and HPLC, respectively. ²¹³Bi-DOTATOC stability was evaluated in rat serum and found to be unchanged after 1 h. Biodistribution studies of ²¹³Bi-DOTATOC were performed in Lewis rats 1 and 3 h post-injection. Data demonstrated specific binding to somatostatin receptor expressing tissues (e.g. pancreas and adrenals). ²¹³Bi-DOTATOC is cleared primarily via the kidneys. In contrast to ²¹³Bi-DOTATOC, administration of free ²¹³Bi resulted in higher accumulation in kidneys and bone marrow