Plain film radiographic examination, the historical standard, is rapidly being supplanted by computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis of sinusitis. In particular, many endoscopic surgeons consider CT to be a mandatory part of the preoperative evaluation. MRI is useful for cases complicated by orbital or intracranial extension. However, because of considerations of cost, the need for sedation, and for CT radiation exposure, conventional x-ray films will continue to play an important role in the diagnosis and management of medically treated sinus disease. Incidental sinus abnormalities in children without apparent symptoms are usually the result of resolving, uncomplicated upper respiratory tract infection. Opacification, moderate-to-severe mucosal thickening, or air fluid levels in patients with persistent symptoms indicate sinusitis. Sinus imaging in children, whatever the modality, is demanding both in obtaining technically adequate studies and interpreting findings. Poor-quality examinations usually overestimate the presence and severity of disease. Ideally, children should be referred to centers with expertise in pediatric ear, nose, and throat imaging.