Unicondylar knee arthroplasty (UKA) is a challenging surgical procedure for many orthopedic surgeons when compared with total knee arthroplasty (TKA). Given the proven similarities in knee biomechanics between UKA and the native knee and recent evidence showing excellent survivorship and functionality, UKA is an excellent alternative to TKA in the appropriate patient. This article discusses the use of intramedullary guides for preparation in partial knee replacement surgery. The concerns of complications arising from cannulating the medullary canal and excessive bleeding have not been seen. The intramedullary UKA yields high levels of success and long-term outcomes, with excellent alignment.