Background: Self-expandable metal stent (SEMS) placement and palliative gastrojejunostomy (GJJ) are palliative treatment options for malignant gastric outlet obstruction. We aimed to compare clinical outcomes of palliative treatments for gastric outlet obstruction caused by unresectable gastric cancer. Methods: We analyzed 217 and 39 patients who underwent SEMS placement and palliative GJJ, respectively, for gastric outlet obstruction caused by unresectable gastric cancer. Results: In total, 217 and 39 patients underwent SEMS placement and palliative GJJ as an initial palliative treatment, respectively. Treatment modality affected re-obstruction after clinical success (hazard ratio [HR] of palliative GJJ (95% confi dence interval [C.I.]) = 0.5 (0.3-0.8). In addition, carcinomatosis with ascites was an independent associated factor of clinical success and re-obstruction (HR (95% C.I.); 0.3 (0.1-0.7) and 1.4 (1.0-2.0), respectively). In a subgroup of patients with good performance who had neither carcinomatosis nor ascites, patency duration and overall survival duration did not differ between the two groups (P=0.079 and P=0.290, respectively). In patients with good performance who had carcinomatosis without ascites, patency duration was longer in the palliative GJJ group than in the SEMS placement group (P=0.016). Overall survival, however, did not differ between the two groups (P=0.062). In a subgroup of patients with good performance who had carcinomatosis with ascites, both patency duration and overall survival were longer in the palliative GJJ group than in the SEMS placement group (P=0.007 and P=0.012, respectively). Conclusions: Long-term clinical outcomes of the palliative treatment modality for gastric outlet obstruction caused by unresectable gastric cancer were affected by carcinomatosis and ascites status.