This chapter presents a discussion about allografts in knee reconstructive surgery. The use of allogeneic tissue has broadened the alternatives that surgeons can use to treat knee disorders. In some cases, the use of allograft tissue may be preferred, or the only, way to reconstruct the defect. Allograft tissue may be procured from cadavers within a few hours of the death of the donor, or from acute post-traumatic amputations with no feasibility for reimplantation or from multiorgan donors. Graft sterility is most commonly ensured by aseptic techniques of harvest and procurement. Currently, the only acceptable methods of allograft preservation are cooling and fresh transplantation within 24 hours, freezedrying, and storage at −80°C or liquid nitrogen storage at −196°C with or without cryopreservation. Careful analysis of synovial fluid after allograft implantation has shown a slight increase in immunomarkers, but a clinically significant reaction does not appear to occur. A detailed discussion on articular cartilage allografts, ligament allografts and meniscal allograft transplantation have been presented in this chapter.