PURPOSE: A successful surgical treatment for a wide alveolar cleft with bone graft is difficult to achieve due to several factors such as limitation of gingivoperiosteal flap, presence of large scar tissues, and poor blood circulation. To overcome these problems, alveolar distraction osteogenesis using Liou alveolar distraction device was applied. We analyzed the consequences of this surgical treatment. METHODS: From January 2006 to August 2007, we have conducted analysis on the methods and consequences of Liou alveolar distraction osteogenesis for 6 patients. The age of patients was 12 years and 6 months on average. The follow up period was 19months on average. The reverse L osteotomy followed by the placement of the Liou alveolar distraction device was performed. After serial distraction, the distractor was removed after 5 months of the process of osteogenesis. The results were analyzed using the computed tomography and the x-ray films of the alveolar bone and the teeth. RESULTS: The alveolar cleft with 12.5mm on average width was filled with 8.5mm of newly formed bone tissue on average width after 5 months of osteogenesis. Among the 6 cases, 5 required the additional bone graft and 1 case only required the gingivoperiosteoplasty. The newly formed bone tissues did not show any signs of bone resorption. However, a considerable degree of teeth displacement was noted. CONCLUSION: For the alveolar cleft too wide to be reconstructed by a general bone graft, it is strongly recommended to perform the reverse L osteotomy of the cleft side with Liou alveolar distraction device to initiate the alveolar osteogenesis. However, the migrated teeth showed some degree of relapse, thus, the orthodontic treatment is essential following the distraction osteogenesis treatment.