A polymerase chain reaction strategy was utilized to identify members of the cadherin family of cell adhesion molecules that are expressed in normal human colon and colon carcinoma. E-cadherin (an epithelial cadherin) and OB-cadherin (a mesenchymal cadherin) were found to be present in the colon specimens. Furthermore, a novel semiquantitative polymerase chain reaction (PCR) assay was developed for each of these two cadherins. These assays were used to determine the relative levels of E-cadherin and OB-cadherin in normal human colon and colon carcinoma specimens. E-cadherin levels were found to be reduced approximately twofold in the adenocarcinoma specimens in comparison to matched normal colon specimens. In contrast, OB-cadherin levels did not correlate with malignant transformation. We speculate that this novel PCR method will be widely applicable for assessing E-cadherin mRNA levels in carcinomas.