Fresh osteochondral allograft (OCA) transplantation has been used to manage a wide spectrum of chondral and osteochondral knee disorders. Basic science and clinical studies support the safety and efficacy of the procedure. Transplantation of viable, mature hyaline cartilage into the affected area is an advantage of the procedure, which can be used to restore bone stock in complex or salvage scenarios. Indications for OCA transplantation in the knee include primary management of large chondral or osteochondral defects and salvage of previously failed cartilage repair. The procedure also can be used for complex biologic knee reconstruction in the setting of osteonecrosis, fracture malunion, or posttraumatic arthritis. Challenges associated with OCA transplantation include allograft storage and size matching, tissue availability, chondrocyte viability, the possibility of immunologic graft response, and a demanding surgical technique. Future research should focus on optimizing allograft viability and healing and refining current surgical indications and techniques.