Recent genetic studies have identified many differentially expressed genes in colorectal carcinomas. For validation of up-regulated genes in colorectal carcinomas, we performed an enzyme-linked immunosorbent assay. Candidate markers were selected from gene expression data for 40 colorectal cancers and 35 matched normal mucosal samples. Based on intensive filtering, 9 genes were selected for the further evaluations. Among them, macrophage migration inhibitory factor (MIF), inhibin betaA, and chemokine ligand 10 were screened, and the results were compared with carcinoembryonic antigen (CEA) in serum samples of 129 patients with colon cancer and 53 healthy control subjects. We found that the serum MIF level was significantly increased in patients with colorectal cancer. Compared with CEA, MIF was more sensitive in early cancer detection (47.3% vs 29.5%). However, the specificity was not as high as that of CEA (90.6% vs 100.0%). Our findings indicate that MIF may be used as a diagnostic marker in colorectal carcinomas.