The function of packaging is to protect the packed food and to maintain its integrity and quality. The package should hinder gain or loss of moisture, prevent microbial contamination and act as a barrier against transfer of oxygen, carbon dioxide and aromatic compounds. Of utmost importance is that the packaging material itself does not promote deteriorative food quality changes or endanger the health of the consumer of the packed food as a consequence of uncontrolled migration of any chemical substances from packaging into food. Recent legislative issues concerning food safety related to migration are summarized. An overview of functional barriers on the market, the sources for and identity of potential migrating substances, and the mechanisms behind migration, as well as of modern analysis techniques, is given. Novel strategies for improvement of functional barriers are discussed. In recent years, increased environmental concern has set the focus on the use of recycled plastics and paper in food packaging, thus enhancing the need for effective functional barriers to prevent contaminants from migrating to food. Future trends in the food packaging market are increased use of biobased polymers, enhanced utilization of nanotechnology for performance improvement and increased use of active or intelligent packaging.