Introduction: Bisphosphonates and denosumab are widely used drugs in patients with bone-consuming diseases, such as osteoporosis, Paget’s disease, hypercalcaemia of malignancy, bone metastases or multiple myeloma. The most important side-effect from the dental point of view is osteonecrosis of the jaw or jaw (medication-related osteonecrosis of the jaw – MRONJ). Risk factors are bone injuries, e.g. tooth extraction and other oral surgical procedures, as well as the use of mismatched restorations, bone exostoses, odontogenic inflammation, poor oral hygiene and coexisting general diseases. Treatment of MRONJ is difficult and long-lasting; therefore, special attention should be paid to the prevention of this disease. Material and methods: The study included 49 patients – 29 women and 20 men. The age range was 54–77, mean age – 64. It was planned to begin bisphosphonate therapy in one patient, another was to start with denosumab therapy. The other 47 patients received BPs or denosumab. 40 of these patients received IV Bisphosphonates, 8 received oral BPs and one received denosumab. Results: During the observation period, which varied from 1–2 years, depending on the patient’s first visit, no signs of MRONJ were observed in the treated areas. There was complete mucosal healing and patients reported no pain. Conclusions: Treatment of MRONJ is difficult and long-lasting; therefore, special attention should be paid to the prevention of this disease.