High quality CT scans are required prior to fibreoptic endoscopic sinus surgery (FESS) surgery and in many institutions such scans are performed using a high mAs technique. Consequently, the investigation imparts a radiation dose to the patient and in particular to the eye. Such a radiation dose is a possible source of morbidity. We believe that the mAs, and consequently the radiation dose, can be considerably reduced without affecting scan quality. The present study compares the quality of sinus CT scans performed at two mAs values, 40 and 60. Scan quality was assessed in terms of the ability to visualize clearly important anatomical structures and in terms of overall perceived quality. We show that mAs values as low as 40 can be used without adversely affecting the diagnostic quality of the examination.