Introduction. The interactions between individual cells as well as between cells and extracellular matrix (ECM) are mediated by cell adhesion molecules (CAM). Over 100 different CAM have been classified into five families: selectins, integrins, cadherins, immunoglobulin superfamily, and CD44. Cell adhesion molecules play important roles in embryogenesis and organ growth, cell migration and leukocyte extravasations, wound healing, coagulation, inflammation and tumour invasion and metastasis. Aim. The aim of this paper is to present the role of CAM molecules in the biology of malignant tumours, including the growth of primary tumour, its progression and organ-specific metastases. Discussion. Cell-cell or cell-ECM interactions determine various biological processes such as cell growth, differentiation and cell migration. These functions are evoked by CAM-mediated intracellular signal transduction. By activating normal or abnormal signalling, CAM become important activators of primary tumour growth, tumour cell migration through ECM and wall of blood and lymphatic vessels, thus enabling organ-specific metastases. It was shown that altered CAM expression in colon, lung, breast and prostate cancer was associated with an adverse clinical course of the disease, faster metastasising and poor prognosis. Preliminary research indicates that cancer-targeted therapy with integrin inhibitors may result in a suppression of tumour angiogenesis and growth inhibition of primary and metastatic tumours. Conclusions. Cell adhesion molecules are useful markers of some types of tumours. Measurement of CAM expression may be used to evaluate the risk of disease recurrence, metastasis formation and survival time. In addition, CAM can be considered as a new group of molecules for targeted cancer therapy.