Neck mass is a common clinical finding in all age groups. Although most neck masses have the nature of benign processes, malignant diseases must ruled out. Careful medical history, such as the duration of the mass, the presence of pain, history of upper airway infection, contact history of animals, and travel, should be obtained. Thorough physical examination should be also performed. The patients' age and the location, size, and duration of the neck masses are important pieces of information. Neck masses in children (0 to 15 years) are more commonly inflammatory than congenital or developmental and those in young adult (16∼40 years) are more commonly congenital than neoplastic. However, the first consideration in elderly adults (>40 years) should be neoplasia. The location of the mass is particularly important with respect to the differentiation between congenital and developmental masses because such lesions are consistent in their location. For metastatic neck masses, their location may be the key to the identification of the primary tumor. Inflammatory and infectious causes of neck masses, such as cervical adenitis and cat?scratch disease, are common in young adults. The progressively increasing size of the mass indicates malignancy, however, a rapid change of size usually suggests an infectious mass. Congenital masses, such as branchial anomalies and thyroglossal duct cysts, should be considered in the differential diagnosis. Neoplasms (benign and malignant) are more likely to be present in older adults. Ultrasonography-guided biopsy is the best diagnostic method for evaluating neck masses. Panendoscopy (nasopharyx, palatine tonsil, base of tongue, piriform sinus, esophagus, stomach, trachea, and lungs) must be performed in all patients of malignant disease. The Open biopsy should be performed only in case of the neck masses which persist beyond four to six weeks after a single course of a broad-spectrum antibiotic or suspects the malignat lymphoma.