We evaluated the usefulness of the following three in vitro assays in cases of resected colorectal liver metastases. Chemosensitivity by collagen gel droplet drug sensitivity test (CD-DST) was very low in all cases, suggesting this method is not predictive for this disease. In contrast, thymidylate synthetase (TS) activity and dihydropyrimidine dehydrogenase (DPD) activity in tumor tissue were high in many patients with recurrent disease. Thus, these enzyme activities are promising for assessment of clinical outcome following hepatic resection of colorectal liver metastases. Further analyses with large numbers of cases are needed to determine the significance of these in vitro studies.