Little is known about the histological effect of hepatic arterial infusion with degradable starch microspheres (DSM), adriamycin (ADM), and mitomycin C (MMC) on liver metastasis of colorectal cancer. We histologically examined hepatic metastases resected following this therapy and investigated their relation to macroscopic changes in size. Neither a histological nor macroscopic effect was found in 2 patients receiving this therapy only one time. A 57-year-old woman with a solitary liver metastasis who received this therapy repeatedly (five times every 3 to 4 weeks) subsequently showed a partial response. She underwent hepatic metastasectomy 5 months after the end of the therapy. Histological examination showed that the greater part of the metastatic lesion was composed of fibrous tissues without any viable cancer cells. In conclusion, it should be noted that repeated infusions of DSM.ADM.MMC for liver metastases of colorectal cancer can have a marked histological effect even though the lesion does not show a complete response.