Objective To study the clinical outcome of comminuted factures at distal femur and proximal tibia treated with AO less invasive stabilization systems (LISS). Methods The clinical data of 14 cases of distal femoral fracture and proximal tibial fracture from September 2003 to May 2005 were analyzed retrospectively. The injury was caused by traffic accident in 9 cases, by fall in 3 cases and by slipping in 2 cases. Of 14 cases, there were 5 open fractures and 9 close fractures, including 5 cases of distal femoral comminuted fracture and 9 cases of proximal shaft comminuted fractures. According to AO/OTA classification, the fractures were classified as 33C2 in 3 cases，33C3 in 2 cases,41A2 in 2 cases，41A3 in 2 cases，41B2 in 3 cases and 41C2 in 2 cases. All patients were treated by the internal fixation with LISS-distal femur or with LISS-proximal tibia. Healing of wounds, the X-ray films before and after operations, and therecovery of joint function were observed. Results The patients were followed up from 1 month to 20 months (11 months on average). Twelve cases achieved solid osseous unions from 3 months to 5 months postoperativly; 2 cases had a good reduction and recovered smoothly 2-3 months postoperatively. The results were excellent in 10 cases, good in 3 cases and fair in 1 case according to Johner-Wruhs knee scoring. The range of knee flexion-extension was 110-130° in 11 cases, 100° in 2 cases and 80° in 1 case. Conclusion LISS is an effective method of internal fixation for treating comminntedfracture of distal femur or proximal tibia. It has the advantages of less injury, satisfied reduction and reliable fixation.