We histologically examined the effect of hepatic arterial infusion of degradable starch microspheres mixed with adriamycin and mitomycin C (DSM therapy) for liver metastases of colorectal cancer. The subjects were 15 liver metastatic lesions from 9 patients with colorectal cancer who underwent potentially curative hepatectomy after DSM therapy. Ages were ranged from 36 to 71 years old (mean, 57). The ratio of male to female was 4 to 5. Six patients had synchronous lesion(s). A single injection dosage of the DSM therapy was comprised of 300-600 mg degradable starch microspheres, 30 mg ADM, and 10 mg MMC. Three lesions from the two patients who were given a single DSM therapy did not show any radiographical changes. In addition, histological examination of these lesions demonstrated a grade 1 effect. The radiographical effect of the 12 lesions from the 7 patients, who were given the DSM therapy at least three times, showed SD in 4 lesions, PR in 6 lesions, and PD in two lesions. Histological examination of these lesions demonstrated Grade 2 in 4 lesions and Grade 3 in 5 lesions. In conclusion, it was histologically confirmed that a repeated DSM therapy could cause satisfactory effects beyond expectations by radiographic imaging in patients with liver metastases of colorectal cancer.