Intercellular and cell-matrix interactions play a crucial role in several physiological and pathological processes. These relationships are based on different cell adhesion molecules. Although adhesion receptors exhibit structural diversity, cell adhesion mechanisms are basically similar to each other. Details of receptor functions (e.g. the exact mechanisms of signal transduction) is poorly understood. In this paper authors summarize data on different cell adhesion antigens and also describe a few important biological features to collect more data on the complex interactions of these molecules.