Computed tomography scans serve as a critical 'roadmap' for functional endoscopic sinus surgery. A systematic evaluation of such scans, and an awareness of any anatomical variants that may modify one's surgical approach, allow one to pre-empt complications. This article describes, from a novice's perspective, two methods of evaluating paranasal sinus computed tomography scans: a quick assessment technique; and a step-wise, operative approach covering radiological features relevant to pre- and peri-operative management.