The alpha emitter Radium-223 ((22)3Ra-Cl2) is a bone-seeking radionuclide studied as a new treatment for patients with bone metastases from hormone refractory prostate cancer. More than 1,000 patients have been included in clinical phase I-III tests showing significant reduction in alkaline phosphatase- and PSA level and prolonged survival. Adverse events are usually mild to moderate and comprise gastrointestinal and myelotoxic symp-toms. Intravenously administered (22)3Ra-Cl2 (half-life 11.4 days) will likely be given every four weeks for six treatments to out-patients.