The aim of this study was to determine if volume of cervical lymph node measured via computed tomography (CT) could differentiate metastatic from benign lesions in head and neck cancer patients. We conducted a retrospective review of chart and images in a tertiary referring center in Taiwan. Patients with head and neck cancers underwent radical, modified radical or functional neck dissection were enrolled. The CT images before operation were reassessed by a radiologist and were compared with the results of pathological examination. A total of 102 patients were included for final analyses. Most patients were male (n = 96, 94%) and average age was 50.1 years. Although the average nodal volume in patients with cervical metastases was higher than those of patients without cervical metastases, it was not an independent factor associated with cervical metastasis after controlling for other variables; however, central nodal necrosis on enhanced CT image [odds ratio (OR) 18.95, P = 0.008) and minimal axial diameter >7.5 mm (OR 6.868, P = 0.001) were independent factors correlated with cervical metastasis. Therefore, the volume of cervical lymph node measured from CT images cannot predict cervical metastases in head and neck cancer patients. Measurement of minimal axial diameter of the largest lymph node is a simple and more accurate way to predict cervical metastasis instead.