The need of efficient antennas in handheld terminals has increased drastically due to the fast development of wireless services. These antennas should be small, efficient and cover multiple frequency bands. But efficiency in antennas is limited by fundamental physical principles, and miniaturizing an antenna is frequently a very challenging task. In this contribution, several aspects of antenna miniaturization will be covered, namely after a short summary on physical limitations, some key aspects in design, analysis and measurement will be highlighted.