Conclusion: The usefulness of addition of positron emission tomography/computed tomography (PET/CT) in decisions as to whether to performneck dissection in patients with T1-T2 lingual squamous cell carcinoma (SCC) might be limited, but adding the condition of lymph nodes with a maximum standardized uptake value (SUVmax) >4.5 to existing criteria would be helpful. Objectives: The purpose of this study was to investigate the usefulness of PET/CT for performing neck dissection in patients with T1-T2 lingual SCC. Methods: This retrospective review surveyed 19 patients with T1-T2 lingual SCC who underwent neck dissection after meeting one or more of the following criteria: (1) clinically positive nodes; (2) >4 mm thickness; (3) >= 3 cm longest diameter of the primary tumor. Focal 18F-fluorodeoxyglucose (FDG) uptake was considered to indicate PET-positive nodes (PET + Ns). The relation between pathologically positive nodes (p + Ns) and PET + Ns was estimated. Results: There were 14 PET + Ns at 12 of 66 levels (18%) in 8 of the 19 (42%) patients. There were also 6 p + Ns (1%) among 412 nodes at 5 cervical lymph node levels (8%) in 5 patients (26%). The sensitivity and specificity for PET/CT were 80% and 64%, respectively. The SUVmax was measured, and receiver operating characteristic (ROC) analysis was undertaken to obtain better accuracy. The sensitivity and specificity were 60% and 100% when the SUVmax cut-off value was set at 4.5.