Our experiment was designed to elucidate the efficacy of continuous intraportal chemotherapy (CIPC) for the prevention of liver metastases. Catheter was introduced into ileocecal vein of white rabbit for administration of adriamycin (ADM). VX2 cells were inoculated into portal vein to form liver metastases. Three experiments were designed as follows: 1) Immediately after inoculation of tumor cells, ADM was administered continuously for 7 days. 2) Continuous administration of ADM started on the 3rd day after inoculation of tumor cells. 3) Immediately after inoculation of tumor cells, ADM was administered by CIPC or systemically for 7 days. The same number of tumor cells were inoculated into portal vein and no treatment was given in control group. The rabbits were sacrificed on the 14th day. Number and size of liver metastases were calculated. Results were as follows: In 1) and 2), the metastases in CIPC group were significantly decreased in number and size compared with those in control group. In 3), no metastasis was observed in CIPC group, but a third of the rabbits developed metastases in systemic group. These results suggest that CIPC is effective for prevention of liver metastases and its efficacy is greater than for systemic chemotherapy.