We evaluated arterial infusion chemotherapy for unresectable metastatic liver tumor using FDG-PET and CT. A 72-year-old female patient with multiple metastatic liver tumors of rectal cancer was treated by arterial infusion chemotherapy. The tumor size decreased by chemotherapy, but there was a high uptake lesion of FDG. Three months later, tumor ingrowth was detected. FDG produces images of regional glycolytic activity, and it is a useful method of assessment of tumor viability after chemotherapy in patients with cancer.