The aim of this study was to compare the diagnostic efficacy of physical examination, ultrasound, and computed tomography for the detection of lymph node metastasis (LNM). Patients with pathologically confirmed squamous cell carcinoma of the head and neck and who were not planned for surgery underwent preoperative physical examinations, ultrasound (US) scans, and computed tomography (CT) scans to detect LNM. Ultrasound-guided fine-needle aspiration cytopathology was the reference standard for calculating the diagnostic parameters. US examination yielded fewer false-negative LNM (P = 0.0125) and higher sensitivity (P= 0.0313), specificity (P= 0.0078), and Youden index (P< 0.0001) than CT examination. The likelihood of detecting LNM with US, CT, and the combination of US and CT as measured in diagnostic confidence/lymph node was >0.718, >0.768, and >0.552, respectively. The combination of US and CT had the least risk of underdiagnosis and higher measures of diagnostic efficacy and predicting outcomes than all other index tests. US has greater diagnostic efficacy than CT in detecting LNM for patients who have no clinical indication for surgery or decline surgical treatment. The combination of US and CT examinations may be a reliable noninvasive method.