There are now two main fields of the ECR ion sources development. The first one consists in going on the upgrade of the current delivered by the sources, mainly in connection with the production of secondary beams. The second one is the study of the improvement of the particle efficiency of sources for the ionization of rare radioactive species. We will make a review of the most advanced devices for production of stable gaseous and metallic ions and specially the high frequency studies dedicated to the ion sources using a 28 GHz gyrotron or higher. We will see that for cyclotrons, the main demand consists in upgrading the current of relatively low charge state ions like in GANIL or MSU. The second aspect is the use of ECR ion sources as high efficiency charge breeder for radioactive ions. This method, called “1+/n+”, consists in injecting and decelerating a monocharged beam extracted from a simple radioactive source and then, in re-extracting the highest number of injected ions as multicharged ions. We wi...