e21084 Background: This study aimed to investigate the efficacy of the Deauville criteria, a 5-point visual scale criteria to assess the maximum standardized uptake value (SUVmax) of [18F]-fluoro-2-deoxy-D-glucose (FDG) on positron emission tomography (PET)/computed tomography (CT), in predicting lymph node metastasis and other pathological invasive characteristics of early-stage lung adenocarcinoma. Methods: In this retrospective study including 453 patients undergoing lobectomy or segmentectomy with lymph node dissection for clinical N0 lung adenocarcinoma with a whole size ≤ 3 cm between April 2011 and March 2019, the FDG-PET/CT scans were evaluated using the Deauville criteria to analyze the relationship of Deauville score with the clinicopathological characteristics and prognosis.The scoring method was as follows: Deauville score of 1, no FDG uptake by the primary tumor (same as background); Deauville score of 2, tumor FDG uptake that is the same as or weaker than that of mediastinum; Deauville score of 3, tumor FDG uptake that is stronger than that of mediastinum but same as or weaker than that of liver; Deauville score of 4, tumor FDG uptake that is moderately higher than that of liver; Deauville score of 5, tumor FDG uptake that is markedly stronger than that of liver. Results: The lymph node metastases were present in 0 (0%), 2 (1.1%), 6 (9.5%), 6 (15.8%), and 13 (15.7%) patients with Deauville scores of 1, 2, 3, 4 and 5, respectively. The pathological invasive characteristics (lymphatic, vascular, or visceral pleural invasion) were detected in 2 (2.4%), 17 (9.9%), 18 (28.6%), 23 (60.5%), and 54 (65.1%) patients, respectively. Similar results were found when the study cohort was analyzed according to the institutions where the FDG-PET/CT scans were performed. The 3-year recurrence-free survival was longer in the patients with a Deauville score of 1–2 (97.2%) than those with a Deauville score of 3 (86.2%, p < 0.001) or 4–5 (80.7%, p < 0.001). Conclusions: The 5-point-scale evaluation of the SUVmax on FDG-PET/CT using the Deauville score was useful in predicting not only lymph node metastasis but also other malignancy characteristics of early-stage lung adenocarcinoma.