The purpose of the present study was to define the indications and extension for the treatment of lymph nodes in clinically NO patients with primary malignant epithelial parotid tumors. A retrospective analysis was performed on 46 cases with such tumor out of 307 parotid neoplasms (246 benign, 61 malignant) consecutively treated from 1985 to 1994. Lymph node metastases were present only in the histotypes with a high degree of malignancy (overall incidence, 24%). Two patients (5%) showed occult metastases. No correlation was found between the size of the neoplasm and the incidence of lymph node metastases. However, the latter were significantly more common in locally highly aggressive neoplasms (class "a"), 8%; class "b" 43%; P = 0.006). Due to the small number of cases, it was not possible to correlate the incidence of occult metastases with neoplasm size or local extension. As regards topographic distribution of lymph node metastases, level II was always involved, level V was never involved, and level i.v was involved only when metastases were found in the upper levels. Occult metastases were found only at level II. Over a follow-up period of 2 to 10 years, no cases were seen with cervical recurrences. Although drawn from a limited series, the results are similar to the data generally reported in the literature, showing that lymph node metastases are rare in neoplasms with a low grade of malignancy whereas there is a significant increase in the incidence of metastatic lymph nodes and occult metastases when the grade of malignancy is high. In conclusion, in clinically NO patients, a suprahomohyoid neck dissection (levels I-II-III) is indicated only when the neoplasm shows a high grade of malignancy or when it is a class "b" malignancy. In the other cases, neck dissection is determined by the clinical evidence of metastasis and can be extended to the lower levels. Neck dissection can be avoided in NO patients whenever ultrasound and fine needle biopsy are both routinely used in the preoperative evaluation of the cervical lymph nodes.