We report successful Y90-radioembolization of the lung applying Y90-resin microspheres via the bronchial artery in two patients with diffuse colorectal and renal cancer metastases, respectively. The deposition of radioactive Y90-resin-microspheres was technically feasible and resulted in a reasonable absorbed dose in the tumors. However, open questions remain regarding dosimetry and safe dose exposure to the lung. The technique warrants thorough investigation before clinical use. A Phase I trial to evaluate safety and preliminary efficacy is under preparation.