Abstract Background Tumours of the gastro-oesophageal junction are amenable to different surgical resections. There is an increasing body of evidence to suggest Siewert type III tumours should be managed as gastric cancers and hence may be more appropriately resected via total gastrectomy. The aim of this study was to compare the outcomes of total gastrectomy and oesophagectomy in patients diagnosed with Siewert type III gastro-oesophageal junction (GOJ) adenocarcinoma. Methods Consecutive patients who underwent curative surgery [total gastrectomy (n=42) or oesophagectomy (n=35)] between 1 January 2010 – 03 April 2023 for Siewert type III GOJ adenocarcinoma were analysed prospectively [median age 68 years, (range 43-83 years), 76.6% male, neo-adjuvant treatment 74.0%]. The primary outcome measure was overall 5 and 10-year survival. Secondary outcomes included: 30- and 90-day mortality, lymph node harvest, positive node harvest, margin involvement, anastomotic leak and length of stay. Results Demographic details between both groups of patients were similar. Patients undergoing total gastrectomy had a significantly shorter length of hospital stay compared with patients undergoing oesophagectomy (median 8 vs. 10 days, p<0.006). Distal margin involvement was significantly higher in patients undergoing oesophagectomy (0% vs. 12.1 %, p=0.027). Overall, 5 and 10-year survival was significantly higher in patients undergoing total gastrectomy (62% and 52% vs. 36% and 22% respectively, p=0.013). There were no significant differences in lymph node harvest (median 29.5 vs. 33.0 nodes), anastomotic leak rates (2.4% vs. 11.4%), 30- (2.4% vs 0%) and 90-day (2.4% vs 2.9%) mortality. Conclusions Patients undergoing total gastrectomy have improved short and long-term outcomes compared with patients undergoing oesophagectomy for Siewert type III GOJ adenocarcinoma.