During the process of invasion, tumor cells must detach from the primary neoplasm and degrade host stroma. E-cadherin is responsible for the cell-cell adhesion and collagenase IV is the one of the matrix metalloproteinases. We determined whether the levels of mRNA for E-cadherin and collagenase IV were differently expressed within 12 cases of early and 13 cases of advanced gastric cancers using a rapid calorimetric in situ hybridization assay for mRNA. In 6 of 12 early cancers, we found a decreased expression of E-cadherin mRNA in the invasion edge compared to the main tumor. In advanced gastric cancers, 3 out of 13 cancers also exhibited this finding. Higher expression of the collagenase IV at the invasion edge of the tumor compared to the main tumor was observed in half of the early and advanced gastric cancer cases. Inverse expression levels of E-cadherin and collagenase IV mRNA were observed in 6 of 12 early cancers. However, only one of 13 advanced cancer cases expressed the same finding.