Purpose The aim of this study was to characterize the patterns of fluorodeoxyglucose (FDG) uptake on F-18 FDG positron emission tomography/computed tomography (FDG PET/CT) at the anastomotic site of gastroduodenostomy after distal subtotal gastrectomy in patients with gastric cancer. Methods From May 2007 to May 2010, two or more follow-up measurements using FDG PET/CT scans were done for 19 patients (11 men, 8 women; mean age, $62.0{pm}10.3$ years) who underwent distal subtotal gastrectomy with gastroduodenostomy between February 2006 and March 2008 for detecting gastric cancer recurrence at our medical center. The FDG PET/CT images were retrospectively reviewed. Patients with local recurrence, regional nodal metastasis or distant metastasis on follow-up studies were excluded. CT and endoscopy were done within 1 month before or after the FDG PET/CT scan. Eight patients had two follow-ups of FDG PET/CT, and 11 patients had three follow-ups. The mean interval between surgery and the first follow-up FDG PET/CT was $12.9{pm}0.8$ months (n=19); between the first and second it was $12.3{pm}1.0$ months (n=19); between the second and third it was $11.6{pm}0.7$ months (n=11). The F-18 FDG uptakes at the anastomotic site and fundus in the remnant stomach were measured by maximum standardized uptake value (SUVmax) using a region of interest technique. Results The SUVmax at the anastomotic site was significantly higher than that of the fundus on all series of first, second and third follow-up studies ($3.3{pm}1.1$ vs. $2.1{pm}0.7$, p<0.001: $3.1{pm}0.9$ vs. $2.2{pm}0.7$, p=0.001: $3.0{pm}0.6$ vs. $2.1{pm}0.7$, p=0.006, respectively). The SUVmax for the anastomotic site and fundus, and SUVmax ratio for the anastomotic site over the fundus were not significantly different throughout the series. Conclusion The SUVmax at the anastomotic site is significantly higher than that of the fundus and does not decrease significantly over time. Therefore, the local recurrence of gastric cancer after surgery could not be definitely differentiated from physiologic uptake or postoperative inflammatory change.