Computed tomography (CT) is the imaging method of choice for conditions that affect the paranasal sinuses. We reviewed all paranasal CT scans in the ear nose and throat (ENT) and maxillofacial surgery departments in 1 year. Of these 372 scans, unilateral opacity of the maxillary sinus was seen in 20 cases. Neoplastic disease was diagnosed in six of these, four of which were malignant. We describe the cases of neoplastic disease, particularly features of the history, examination, and scans that should alert the clinician to the possibility of sinister pathology. We emphasise the importance of nasendoscopic examination in the accurate assessment of sinonasal disease.