The Wnt/b-catenin signalling pathway plays crucial roles in development and its aberrant activation is an initial and crucial event in the majority of colon cancers. The Dickkopf-1 (Dkk-1) gene encodes an extracellular Wnt inhibitor that blocks the formation of signalling receptor complexes at the plasma membrane. Here, we report the serum levels of Dkk1 in colorectal cancer patients without any therapy. The levels were determined by enzyme-linked immunosorbent assay (ELISA) in 135 colon and 160 rectum cancer patients, as well as 90 healthy subjects. Data analyses were performed using SPSS software (SPSS 16, Chicago, IL). There were no significant differences among the groups for Dkk-1 (p=0.363). In conclusion, the present study did not confirm that serum Dkk-1 levels could have any diagnostic potential in colon and rectum cancers.