In patients with laryngeal carcinoma, nodal metastasis, recurrence after radiotherapy, and prognosis are important factors in clinical decision-making. Parameters such as tumor stage are considered insufficient for predicting these important items. The DNA ploidy status of the tumor may be a useful additional marker. The DNA ploidy status of 38 laryngeal cancers was determined by flow cytometry. Correlations were studied with TNM stage, differentiation, survival rate, relapse risk, recurrence after radiotherapy, and nodal metastasis. A positive correlation of DNA ploidy status with the development of lymph node metastases was found for diploid and peridiploid versus aneuploid tumors (DNA index, <1.4 versus > or = 1.4; p = .007). No correlation was found between ploidy status and recurrence after radiotherapy. The overall survival rate (p = .01), but not the disease-specific survival rate or the relapse risk, showed a correlation with the ploidy status. The DNA ploidy status may be a useful marker for metastatic behavior in head and neck squamous cell carcinoma and may therefore be helpful in decision-making concerning elective treatment of the neck.