In progression of tumours, resulting from, i.e., release of cells from the parental tumour and development of metastases, expression of cell adhesion molecules (CAM) plays a significant role. CAM, including E-cadherin and the linked to it beta-catenin, determine the extent of adhesion between normal and neoplastically altered cells. Moreover, the unbound form of beta-catenin in a cell nucleus may affect the rate of cell proliferation This study aimed at demonstrating intensity and localisation of E-cadherin and beta-catenin expression as related to expression of the proliferation-associated antigen, Ki-67 in mammary adenocarcinomas of bitches. The study was performed on 35 cases of the above mentioned tumours. On paraffin sections immunohistochemical reactions were performed using monoclonal antibodies directed against E-cadherin, beta-catenin and Ki-67 antigen. In the studies a membranous expression of E-cadherin, a cytoplasmic-nuclear expression of beta-catenin and nuclear expression of Ki-67 antigen were demonstrated. Statistical calculations using Spearman's test demonstrated a pronounced positive correlation between expression of beta-catenin and Ki-67 antigen and absence of correlation between expression of E-cadherin and Ki-67 antigen. No correlation could be detected between expression intensities of E-cadherin and beta-catenin.