Objective To investigate the safety and effectiveness of peroral endoscopic myotomy (POEM) in the treatment ofachalasia (AC) patients with variant esophageal morphologies. Methods A prospective study was conducted. From November 2022 toDecember 2024, patients diagnosed as AC and treated with POEM at the department of gastroenterology in our hospital were selected.Based on the Japanese Esophageal Society’s classification criteria, the patients were divided into a straight-type esophagus group (Stgroup, n=27) and a sigmoid-type esophagus group (Sg group, n= 13). The St group had lower esophageal long-axis angle≥135°.The Sg group including aSg had lower esophageal long-axis angle <135°. Preoperative, intraoperative parameters, and postoperativeoutcomes were compared between the two groups. Results Symptom duration, esophageal dilation diameter on barium esophagography,and proportion of patients with prior treatments in the Sg group were longer or larger or higher than those in the St group (P<0. 05).There were no significant differences in Eckardt scores, gender, age, body mass index (BMI), age of onset, data of high-resolutionmanometry (HRM) and diameter of lower esophageal stenosis on barium esophagography between the two groups (P>0. 05). Therewere no significant differences in operative time, intraoperative bleeding, and postoperative adverse events between the two groups (P>0. 05). Postoperative Eckardt scores of both groups were≤3. However, there was significant difference when the Eckard scores of the40 patients before surgery were compared with those after 3 months and 6 months of surgery (P<0. 001). There were no significantdifferences in pre-to-postoperative Eckardt score changes, incidence of postoperative gastroesophageal reflux disease (GERD) and postoperative hospital stay (P>0. 05). Conclusions Sg-type AC patients have longer symptom duration and higher rates of prior interventions compared to St-type patients. However, disease progression is not correlated with symptom severity. POEM is a feasible, effective, and safe treatment for AC patients with both St-type and Sg-type esophageal morphologies.