A polymerase chain reaction-based approach was used to study the expression of Wnt genes in human colon carcinoma tissue and normal colon mucosa. In a number of cases Wnts 2, 4, 5a, 6 and/or 7a were found to be more highly expressed in colon carcinoma tissue compared to surrounding normal-appearing mucosa from the same patients. Wnts 4, 5a, 6 and 7a, but not 2, were also found to be expressed in colon cancer cell lines. The increased levels of expression of these Wnt genes in tumor tissue may indicate their possible involvement in human colon tumorigenesis.