Magnetically controlled intramedullary lengthening nails (MCILN) have revolutionized the field of limb lengthening and deformity correction. They allow for accurate and precise distraction with excellent patient outcomes and satisfaction. Though potentially technically easier than external fixation, general deformity principles and bone and soft-tissue biology must be considered for successful use. MCILN can address deformities of a wide range of etiologies including congenital, posttraumatic, post-infectious, tumor, and many others with excellent healing rates and outcomes as well as better patient satisfaction and similar cost compared to external fixation. Of the approximately 10,000 MCILN that have been implanted (written communication, NuVasive, Inc., San Diego, California), about 749 cases have been reported in the published literature. Applications outside of deformity correction are on the rise, with new uses reported in reconstruction after tumor resection and acute trauma. This review of MCILN summarizes the history, recent advances, and results of MCILN treatment in a multitude of clinical applications.