Abstract: Objective To evaluate the outcomes of open high tibial osteotomy through small incision with annular external fixator for treating genu varum deformity. Methods We reviewed 8 cases of open high proximal tibia osteotomy through small incision with annular external fixator for patients (10 knees) with genu varum due to high tibia varum. The patients were followed up 1, 2, 3, 6, 12, 24 and 36 months after the operations. Data about infection, healing, varus angle, knee distance and Insall-Salvati index were retrieved and analysed. Results The patients had a mean varus angle of 15.3°±2.3° (range,10°-28°) before the operations. The operations were all recorded as successful following a (29.3±3.1) mouth (range, 24-36 months) post-operation follow-up, with external fixator remaining stable and no instrument failures. The bones were healed at an average of (11.2±1.5) weeks (range, 8-12 weeks) and there was no nonunion or delayed union. The operations reduced varus angle of the knees to -1.1°±0.6° (range, -7°-3°), indicating a significant improvement compared to that of the pre-operations. There were 2 cases of superficial pin infections. Conclusion Open high tibial osteotomy through small incision with annular external fixator has good fixation stability and satisfactory clinical outcomes with little complications for treating patients with genu varum deformity.