Hen egg proteins are desirable ingredients of many foods. Today, eggs are widely distributed in international trade and the egg industry is an important segment of the world food industry. Hen egg proteins have unique functional properties such as gelling, foaming (egg white) and emulsifying (egg yolk) properties. This review describes the recent advances in molecular basis of the development of these functional properties as well as technical development of new approaches for improving the functional properties of egg proteins. A better understanding of structure-function relationship of egg protein functionality in food system will enable us for tailoring food protein for specific uses.