This study compared the safety and efficacy of peroral endoscopic myotomy for esophageal motility disorders between octogenarians and non-octogenarians. Methods: This retrospective observational study recruited 321 patients (28 octogenarians and 293 non-octogenarians) who underwent peroral endoscopic myotomy from two institutions. Clinical success (postoperative Eckardt score ≤ 3), technical success (completion of gastric and esophageal myotomy), and perioperative adverse events were compared between octogenarians and non-octogenarians. Perioperative adverse events were classified into major and minor adverse events based on the International Peroral Endoscopic Myotomy Survey criteria and were subdivided into technical and nontechnical adverse events according to the presence of a direct causal relationship with the procedure. Results: There were no significant differences in the rates of clinical success 1 year after treatment (100% vs. 97.3%, P = 0.64) and technical success (100% vs. 99.7%, P = 0.91) between octogenarians and non-octogenarians. Octogenarians had a higher incidence of perioperative adverse events (28.6% vs. 10.2%, P = 0.00097), particularly major adverse events (25.0% vs. 3.0%, P < 0.0001). There were no significant differences in the incidence of minor adverse events (7.1% vs. 7.9%, P = 0.67). Although there was no difference in the incidence of technical adverse events (10.7% vs. 9.2%, P = 0.74), octogenarians had a significantly higher incidence of non-technical adverse events (17.9% vs. 1.0%, P = 0.0002). Conclusions: There were no significant differences in shortterm clinical success and technical success between octogenarians and non-octogenarians. However, octogenarians showed a significantly higher incidence of perioperative adverse events, particularly in major adverse events and nontechnical adverse events. Peroral endoscopic myotomy for octogenarians should be carefully applied.