Neck masses in children most often represent benign lymphadenitis due to infection. The involved lymph nodes are usually small, shotty, diffusely distributed, and superficial. They may be tender and associated with an acute upper respiratory infection or with chronic infection of the tonsils and adenoids. Enlargement of the jugulodigastric node is most often associated with tonsillitis, and the spinal accessory group of nodes with adenoiditis. Acute viral diseases may be associated with lymphadenopathy; mononucleosis is the most striking example. The differential diagnosis must include deep neck-space abscesses, congenital cysts, and benign as well as malignant neoplasms. A diagnosis can be derived from a consideration of the history and physical findings, the age of the patient, and the location, size, and consistency of the mass. A careful otolaryngologic exam--including the nasopharynx, a chest radiograph, and appropriate blood studies--should be routine. When malignancy is suspected, a biopsy of the mass is indicated.