Surgical resection of lung metastases is a widely accepted procedure but long-term results are disappointing with a 5-year survival rate of approximately 40%. The main prognostic factor is complete resection and a better survival is reported in patients with a single metastasis and a disease-free survival of more than 3 years. Re-operations are feasible but often patients become inoperable due to insufficient pulmonary reserve and new treatment modalities are looked for. Intravenous (iv) chemotherapy has no major impact on survival due to systemic side-effects when high doses are given. As isolated limb and liver perfusion, isolated lung perfusion (ILuP) has the advantage of selectively delivering an agent into the lung while diverting the venous effluent. This allows the drug to be given in a significantly higher dose compared to iv therapy, while drug levels in the other organs are kept low enough to avoid major complications. ILuP has been shown to be very effective for the treatment of lung metastases in animal models. Phase I clinical studies to determine dose-limiting toxicity and maximum tolerated dose have recently been reported. The principal aim of this book is to discuss the current treatment of lung metastases and the possible contribution of ILuP.