A wide range of masses develop in the nose, nasal cavity, and nasopharynx in children. These lesions may arise from the nasal ala or other structures of the nose, including the mucosa covering any surface of the nasal cavity, the cartilaginous or osseous portion of the nasal septum, the nasal turbinates, and the nasal bones. Lesions may also arise from the nasopharynx or adjacent structures and involve the nose by way of direct extension. The causes of nasal masses in children include congenital and developmental disorders such as congenital nasolacrimal duct mucocele, dermoid cyst, cephalocele, and nasal neuroglial heterotopia; inflammatory and infectious processes such as mucocele, polyp, and pyogenic granuloma; benign neoplasms such as infantile hemangioma and juvenile nasopharyngeal angiofibroma; malignant lesions such as rhabdomyosarcoma and nasopharyngeal carcinoma; and masses related to prior trauma such as septal hematoma. Although direct visualization, without imaging, is frequently sufficient to diagnose pediatric nasal conditions, in many cases imaging has a key role in the treatment of the affected child. Some of these lesions have characteristic computed tomography and/or magnetic resonance imaging findings, some of them are diagnosed on the basis of the location and imaging findings combined, and others demonstrate nonspecific imaging findings. However, imaging is important for better defining the total extent of the lesion and guiding the clinician in determining whether medical and/or surgical intervention is required. In this article, the authors review the imaging findings of the most common causes-and many of the not-so-common causes-of nasal masses encountered in the pediatric population. ©RSNA, 2017.