[en] Six cyclotrons using superconductivity are now producing beams. Three more are nearing completion and designs are progressing for yet newer machines. Most of these cyclotrons are dedicated to nuclear physics research, but two are used for neutron radiation therapy and isotope production, respectively, and have their small size as most significant feature. The design and the limitations of existing superconducting cyclotrons, as well as possible future developments are discussed. Cyclotrons with different design, currently in the stage of construction, design or conception are briefly reviewed. (author) 26 refs.; 10 figs