8 p. ; Background: Colorectal cancer (CRC) is the second most common cause of death from cancer in both men and women in the majority of developed countries. Molecular tests of blood could potentially provide this ideal screening tool. -- Aim: Our objective was to assess the usefulness of serum markers and mRNA expression levels in the diagnosis of CRC. -- Methods: In a prospective study, we measured mRNA expression levels of 13 markers (carbonic anhydrase, guanylyl cyclase C, plasminogen activator inhibitor, matrix metalloproteinase 7 (MMP7), urokinase-type plasminogen activator receptor (uPAR), urokinase-type plasminogen activator, survivin, tetranectin, vascular endothelial growth factor (VEGF), cytokeratin 20, thymidylate synthase, cyclooxygenase 2 (COX-2), and CD44) and three proteins in serum (alpha 1 antitrypsin, carcinoembryonic antigen (CEA) and activated C3 in 42 patients with CRC and 33 with normal colonoscopy results. -- Results: Alpha 1-antitrypsin was the serum marker that was most useful for CRC diagnosis (1.79 +/- 0.25 in the CRC group vs 1.27 +/- 0.25 in the control group, P