[Objective]To analyze the reasons of complications in high tibial valgus osteotomy in the varus osteoarthritic knee and its management.[Method]We studied the results of valgus-producing high tibial osteotomies in patients who had medial unicompartmental osteoarthritis and varus malalignment.We performed the operation for 126 patients from January 2000 to October 2004.Twenty-one patients had complications,including four men and seventeen women,with average age of 61 years(ranged:48～64 years).The femorotibial angle was measured on the standing anteroposterior film of knee preoperatively in order to get high accuracy in preoperative planning.A lateral closing-wedge osteotomy was performed,the osteotomy site was stabilized by Giebel blade plate or stepped staple.[Result]The mean duration of follow-up was 7.5 months(ranged,6 to 12 months).There were twenty-three complications(21 patients,16.7%):tibial fracture in four cases,deep-vein thrombosis in five cases,peroneal nerve palsy in three cases,recurrence of varus deformity in six cases,internal fixation failure in four cases(recurrence of varus deformity developed in two patients),a superficial wound infection developed in one patient.[Conclusion]To reduce the incidence of complications in high tibial valgus osteotomy,we should make familiarication with anantomy and take more accuracy in preoperative planning,improve surgical skill as well as appropriate perioperative management.