ObjectiveBisphosphonate-related osteonecrosis of the jaw (BRONJ) is a rare but serious side effect of bisphosphonates (BPs). Since this disease has no independent code in either of the diseases’ or in the medical procedures’ classifications, it is hard to estimate how many BP patients are affected.DesignA retrospective observational epidemiological registry-based study was carried out, using the data of the national service of Hungary on the incidence of BRONJ and related factors.SettingA data analysis was performed, which is relevant for the whole Hungarian population from 2010 to 2014. The socioeconomic and medication data of 236 207 BP patients were analysed, and a method was worked out to define BRONJ patients from the Hungarian BP population.Primary and secondary outcome measuresThe incidences of BRONJ were analysed according to genders and the types of the BP drugs administered. The marginal interdependence between the types of BP drugs, modes of administration and main indication was calculated.Results340 BP patients (0.1%) developed BRONJ. The incidence of BRONJ in Hungary in the malignant indication of BPs is 0.9%, and 0.1% in the non-malignant indication, and the OR to develop BRONJ was OR=9.7 (95% CI 7.8 to 12.1) between them. Although more women developed BRONJ, the proportion of men was significantly higher than that of women. Steroids increase the risk of jaw osteonecrosis, and differences were also found between the BP drugs.ConclusionsOncology indicated, intravenously administered and steroid comedicated BP therapies pose a high risk of developing BRONJ in the Hungarian population.