The aim of this retrospective study was to analyse the outcome of alveolar distraction osteogenesis for the correction of vertical defects in a large series of 55 cases. The existing bone deficiencies were secondary to atrophy after periodontal disease or tooth extraction. The overall success rate of this technique was 89.1%. The complications presented during treatment were divided into minor (no effect on final result, but immediate intervention required) 14/55 patients (25.4%), and major (lead to technique failure) 6/55 patients (10.9%). The frequency of minor complications was 8/27 in the anterior maxillary region, 1/27 in the anterior mandibular region and 15/27 in the posterior mandibular region. The frequency of major complications was 5/6 in the posterior mandibular region and 1/6 in the anterior maxillary region. The mean alveolar height achieved was 6mm. The overall rate was 36.3%. On the basis of these results it was concluded that alveolar distraction osteogenesis is an effective technique to treat vertical alveolar ridge deficiencies.