A consecutive series of 1,081 previously untreated patients undergoing 1,119 radical neck dissections (RNDs) for squamous carcinoma of the head and neck was reviewed to study the patterns of nodal metastases. Primary tumors were located in the oral cavity in 501 patients, in the oropharynx in 207 patients, in the hypopharynx in 126 patients, and in the larynx in 247 patients. Lymph node metastases were confirmed histologically in 82% of 776 therapeutic neck dissections, and micrometastases were discovered in 33% of 343 elective RNDs. Lymph node groups in the neck were described by levels (I to V). Predominance of certain levels was seen for each primary site. Levels I, II, and III were at highest risk for metastasis from cancer of the oral cavity, and levels II, III, and IV were at highest risk for metastasis from carcinomas of the oropharynx, hypopharynx, and larynx. Supramohyoid neck dissection (clearing levels I, II, and III) for NO patients with primary squamous cell carcinomas of the oral cavity and anterolateral neck dissection (clearing levels II, III, and IV) for NO patients with primary squamous cell carcinomas of the oropharynx, hypopharynx, and larynx are recommended.