The purpose of this study was to identify the patient populations at risk of medication-related osteonecrosis of the jaw (MRONJ) and determine which medical and dental comorbidities are significant risk factors for this disease. An electronic search of Embase, MEDLINE, Cochrane Central Register of Controlled Trials, WHO International Clinical Trials Registry Platform and ProQuest Dissertations and Theses Global was conducted to identify all human studies that reported risk factors for MRONJ. Only a qualitative analysis was performed due to significant heterogeneity in the collected data. The search strategy identified 2872 records, of which 219 studies were eligible for inclusion. A total of 4106 patients with MRONJ were identified, 39 different systemic diseases were implicated, and 14 medical and 11 dental risk factors were reported, although no statistical analysis of the significance of each of these factors was possible. The clinical reach of MRONJ may be wider than anticipated, and more data on the significance of each potential risk factor are needed to guide the identification and management of at-risk patients.