Dielectric lens antennas are attracting a renewed interest for millimetre-and submillimetre wave applications where they become compact, especially for configurations with integrated feeds usually referred as integrated lens antennas. Lenses are very flexible and simple to design and fabricate, being a reliable alternative at these frequencies to reflector antennas. Lens target output can range from a simple collimated beam (increasing the feed directivity) to more complex multi-objective specifications.This chapter presents a review of different types of dielectric lens antennas and lens design methods. Representative lens antenna design examples are described in detail, with emphasis on homogeneous integrated lenses. A review of the different lens analysis methods is performed, followed by the discuss ion of relevant lens antenna implementation issues like feeding options, dielectric material characteristics, fabrication methods and a few dedicated measurement techniques. The chapter ends with a detailed presentation of some recent application examples involving dielectric lens antennas.