High tibial osteotomy has been established as an effective surgical intervention in patients with unicompartment osteoarthritis of the knee associated with varus deformity and abnormal load through the medial compartment. The aims of this study were to report the result of open-wedge osteotomy performed with allograft bone and also to evaluate the postoperative clinical results in a series of patients. There are still little medical literatures regarding the use of an allograft bone transplant in open-wedge osteotomy. 37 consecutive cases that had undergone opening wedge osteotomy using allograft bone were studied. They were followed each 2 months after surgery until 6 month. There were 7 men and 30 women, aged ranging from 16 to 66. All patients were followed 6 months after surgery until clinical and radiographic healing of the osteotomy site. All patients could stand and walk on operated limb 6 months after operation, but 11 of them had still pain after this duration. There were no cases of non-union or osteotomy site collapse associated with the use of allograft. Moreover, no significant complication has been detected in these patients with choosing appropriate patients and performing good surgical technique, and the proximal tibial wedge allograft is a satisfactory choice that provides effective clinical and radiographic bone union.