Osteonecrosis of the jaws (ONJ) in patients receiving bisphosphonates is currently being discussed in the scientific literature. Oral bisphosphonates such as alendronate are commonly used to treat osteoporosis and have rarely been associated with ONJ in the benign setting. There is a greater number of reported ONJ cases in patients using intravenous bisphosphonates such as pamidronate and zoledronic acid for cancer-related indications. Many authors have associated local factors, such as dental extraction, periodontal disease, abscesses, and other oral problems, with the development of ONJ, and some have also suggested risk factors other than dental irritation. The aim of this study was to describe the clinical data from oncology patients with ONJ from a single institution. A total of 18 ONJ cases were identified among all patients treated at or referred to our institute (Hospital do Cancer A C Camargo, Sao Paulo, Brazil). These patients had a variety of primary malignancies: breast cancer (n = 7), multiple myeloma (n = 4), prostate cancer (n = 3), lung cancer (n = 3), and renal cancer (n = 1). Current bisphosphonate therapy included zoledronic acid (n = 15; 7 [47%] had received prior pamidronate therapy), pamidronate (n = 2), and alendronate (n = 1). The ONJ cases were managed conservatively using local irrigation with 0.12% chlorhexidine gluconate, debridement, and antibiotics. A total of 29 local ONJ lesions were found: 13 patients had 1 lesion, 3 patients had 2 lesions, and 2 patients had 5 lesions. The majority (n = 16 [89%]) of the patients experienced some level of local discomfort/pain, 6 complained of halitosis, and only 2 patients were asymptomatic. Clinically, 62% of the ONJ lesions were associated with dental work and extractions; only 20% occurred spontaneously. The majority (59%) of the ONJ lesions completely healed in 9 patients. Overall, most of the ONJ lesions were associated with dental procedures, and pain was the symptom most frequently reported. Excellent dental hygiene was found to be important for preventing infections and ONJ and also to contribute to lesion healing in the majority of the cases.