Colorectal cancer (CRC) is one of the most common cancers worldwide usually diagnosed in the advanced stage. The serum concentration of tumor endothelial marker 1 (TEM1) was measured and correlated with clinicopathological features to evaluate whether TEM1 might serve as a biomarker for early CRC diagnosis, progression, and prognosis. TEM1 can act as a potential diagnostic, progression, and prognostic serum biomarker for patients with CRC; TEM1 might be a good supplement for commonly used markers CEA and Ca 19-9.