Adhesion molecules mediate cell-cell and cell-matrix interactions and are essential for numerous physiological and pathological processes. Recent evidence from many laboratories suggests that adhesion molecules play an important role in tumor progression and may promote tumor growth and organ-specific metastasis. Certain adhesion molecules may also function as tumor suppressors. In this review, we describe current concepts concerning the role of the adhesion molecules in the pathogenesis of cancer and the development of therapeutic approaches which make use of this information. Hence, by preventing tumor cells from interacting with each other or with their microenvironment, tumor growth and metastasis can be suppressed. The feasibility of using anti-adhesion strategies to treat cancer has been demonstrated in many animal models. Thus, monoclonal antibodies (MAbs) against adhesion molecules, synthetic peptidic and nonpeptidic analogues of the recognition sequences on their receptors, soluble adhesion molecules and antisense oligonucleotides can inhibit tumor growth and gene therapy can restore the functions of altered tumor-suppressive adhesion molecules.