OBJECTIVE There are no data available to show whether there is a relationship between mandibular fractures and isolated fractures of the posterior and/or lateral walls of the maxillary sinus. The aim of this study was to determine whether there is a coincidence between these fracture patterns. METHODS Four hundred large volume cone beam computed tomography scans (CBCT) of patients with a fracture of the mandible between 2008 and 2013 were analyzed retrospectively. Patients with multiple midfacial fractures were excluded. The radiographic findings were correlated with epidemiological and clinical data of the patients such as gender, age, treatment methods, or complications. RESULTS The most frequent fracture sites of the mandible were the jaw angle, the parasymphysis region, and the condyle. Nineteen of the 400 patients (4.75%) had an isolated fracture of the lateral and/or posterior maxillary sinus. Odds-ratio analysis revealed a high tendency for significant correlation of condylar process fractures with isolated maxillary sinus fractures. Chi-square test demonstrated a P-value near statistical significance (P=.054). No other fracture site of the mandible could be associated with an isolated fracture of the maxillary sinus. CONCLUSIONS A condylar process fracture of the mandible after trauma without any further injury of the midface may be associated with an isolated fracture of the lateral and/or posterior maxillary sinus.