Purpose: In this study, we introduced an newly developed technique of operation for fracture of lateral malleolus of the ankle. We treated the fracture by close reduction and internal fixation using arthroscopy. Materials and Methods: From July 2006 to June 2007, we had treated 23 cases of lateral malleolar fracture (SER type) by closed reduction and internal fixation with arthroscopy and followed them up more six month. Operation time, union time, clinical and functional result were evaluated. Results: After the final follow-up, all the fractures were healed with satisfactory bony union. The subjective result was excellent in 15 cases (65%), good in 8 cases (35%), the objective result was excellent in 13 cases (57%), good in 10 cases (43%), and the roentgenographic result was excellent in 17 cases (74%), good in 6 cases (26%). Conclusion: Closed reduction and internal fixation with arthroscopy technique is an effective treatment method in treating lateral malleolar fracture of the ankle since it offers advantages including corrective anatomical reduction and minimizing complication associated with injury of soft tissue.