The identification of patients at higher risk of recurrence after primary colorectal cancer resection is currently one of the challenges facing medical oncologists. Circulating tumor cell (CTC) may represent a surrogate marker of an early spread of disease in patients without overt metastases. Thirty-seven high-risk stages II-III colorectal cancer patients were evaluated for the presence of CTC. Enumeration of CTCs in 7.5 ml of blood was carried out with the FDA-cleared CellSearch system. CTC count was performed after primary tumor resection and before the start of adjuvant therapy. CTC was detected in 22 % of patients with a significant correlation with regional lymph nodes involvement and stage of disease. No significant correlation was found among the presence of CTC and other clinicopathological parameters. These data suggest that CTCs detection might help in the selection of high-risk stage II colorectal cancer patient candidates for adjuvant chemotherapy.