PURPOSE: To evaluate the clinical results of the surgical treatment for established nonunion of lateral humeral condyle fracture using closing wedge osteotomy and bone graft. MATERIALS AND METHODS: Six patients diagnosed as symptomatic established nonunion of lateral humeral condyle fracture and cubitus valgus deformity were reviewed retrospectively. The average age was 23 years old and mean follow up period was 32 months. We investigate the changes of the symptoms and radiographic findings, and determine the results by Oppenheim's criteria. RESULTS: According to Oppenheim's criteria, 3 patients showed excellent, 2 good, 1 poor. Carrying angle is improved to 10.2 degrees and range of motion was decreased by mean 9 degrees. All of the patients' muscle weakness and pain were improved, and was achieved solid union at the last follow up. CONCLUSION: In the treatment of symptomatic established lateral humeral fracture and cubitus valgus deformity, better functional and cosmetic results are anticipated by a closing wedge osteotomy and bone graft.