Periodontal diseases and dental diseases are proved as a significant role for Medication related osteonecrosis of the jaw(MRONJ) from many studies. But there has been no study of whether periodontal disease affects not only the onset of MRONJ but also the progression of MRONJ. Thus, The aim of this study is to prove the influence of periodontal infection upon the stage of MRONJ. This study included 86 patients diagnosed with MRONJ, who visited the Department of Dentistry, Oral & Maxillofacial Surgery at Ajou University Hospital from August 2006 to September 2016. Each patient with MRONJ was staged according to the 2014 American Association of Oral and Maxillofacial Surgeons(AAOMS) MRONJ position paper. Each patient’s alveolar bone height was measured by panoramic radiography using Bjorn and Holmberg’s method. There was a significant difference in the alveolar bone height between the MRONJ groups with and without MRONJ infection as seen by the independent t-test (p = 0.004 < 0.05). From this study, Periodontal infection can affect both the risk for developing MRONJ and also the MRONJ stage.