5-FU hepato-arterial infusion (HAI) is powerful chemotherapy for liver metastases of colorectal cancers. Event though hepatic lesions are controlled by 5-FU HAI, we have found that extra-hepatic lesions are the limiting factor for colorectal cancer patients. General chemotherapy is necessary in addition to 5-FU HAI. The chemotherapy of 5-FU venous infusion plus oral UFT is called "pharmacokinetic modulating chemotherapy (PMC)." This protocol is very effective for colorectal cancers, because UFT reduces the rate of metabolism of infused 5-FU. We studied the plasma 5-FU concentration at the time of weekly high dose 5-FU HAI plus oral UFT. The plasma concentration of 5-FU in 5-FU HAI plus UFT is 1.5-6 times as high as with 5-FU HAI only. 5-FU concentration in the liver tissue is likely to be much higher at the time of 5-FU HAI. 5-FU HAI plus oral UFT can be more effective for not only liver metastases but also for extra-hepatic lesions than 5-FU HAI alone.