Background Peroral endoscopic myotomy (POEM) has been developed to provide a less-invasive myotomy for achalasia in adults but seldom has been used in pediatric patients. Objective To evaluate the feasibility, safety, and efficacy of POEM for pediatric patients with achalasia. Design Single-center, prospective study. Setting Academic medical center. Patients A total of 27 pediatric patients (mean age 13.8 years, range 6-17 years) with achalasia. Interventions POEM. Main Outcome Measurements The primary outcome was symptom relief during follow-up, defined as an Eckardt score of ≤3. Secondary outcomes were procedure-related adverse events, clinical reflux adverse events, and lower esophageal sphincter (LES) pressure on manometry before and after POEM. Results A total of 26 cases (96.3%) underwent successful POEM. A submucosal tunnelling attempt failed in 1 case because of serious inflammation and adhesion. No serious adverse events related to POEM were encountered. During a mean follow-up period of 24.6 months (range 15-38 months), treatment success was achieved in all patients (mean score before vs after treatment 8.3 vs 0.7; P  < .001). Mean LES pressure also decreased from a mean of 31.6 mm Hg to 12.9 mm Hg after POEM ( P  < .001). Five patients developed clinical reflux adverse events (19.2%). Limitations Single center and lack of some objective evaluations. Conclusion This relatively long-term follow-up study adds to the evidence that POEM seems to be a promising new treatment for pediatric patients with achalasia, resulting in long-term symptom relief in all cases and without serious adverse events.