The adhesion molecule E-cadherin has been shown to influence malignant transformation of tumors, including local and distant metastases. We examined the expression of E-cadherin to determine its relationship to the development of metastasis in metastatic brain tumors. Immunohistochemistry for E-cadherin and Ki-67 was carried out in 76 formalin-fixed, paraffin-embedded archival specimens of metastatic brain tumors and in 14 corresponding available primary tumors from patients who received treatment for metastatic brain tumors. The primary tumors were mainly lung cancers (51.3%), followed by gastrointestinal tumors (28.9%). E-cadherin was expressed in 62 (81.5%) of 76 cases examined. In metastatic adenocarcinomas, a consistent tendency for E-cadherin expression was noted, regardless of the degree of differentiation or the extent of spread of the disease (P = 0.04). There was a direct correlation between E-cadherin expression and high MIB-1 index in all metastatic brain tumors (P = 0.0007). Pairwise analysis in 14 primary tumors and the corresponding metastatic specimens revealed high E-cadherin and MIB-1 staining in metastatic brain tumors. These results provide a unique association between E-cadherin, systemic metastasis, and proliferation potential in metastatic brain tumors.