We have developed a pulmonary arterial infusion therapy for lung metastasis of colorectal cancer. Catheterization into pulmonary artery followed by occlusion with ballooning enabled the stasis of blood flow in the unilateral lung for 30 minutes. CDDP was infused via catheter to occluded pulmonary artery. Although no serious adverse events occurred in 5 cases, a tumor reduction in size was not observed. Loco-regional therapy for lung metastasis of colorectal cancer is limited because of recent progress of systemic therapy. However, a development of the procedure of pulmonary arterial infusion may enable a future success of local therapy for lung metastasis of colorectal cancer with a new drug, which is effective in such a short time disposure to tumor as 30 minutes.