INTRODUCTION:Per-oral endoscopic myotomy (POEM) is an effective modality for the management of achalasia. Tension pneumoperitoneum is a significant complication that causes hemodynamic instability, generally within the periprocedural period. METHODS:Here, we report 2 cases of delayed tension pneumoperitoneum that was recognized and treated several hours after uncomplicated POEM. RESULTS:These cases illustrate the importance of continued vigilance for this complication outside of the immediate periprocedural period as well as the utility of computed tomography-guided aspiration in managing it. DISCUSSION:When discharging patients after POEM, caregivers should be aware of this rare complication and alert patients to return for immediate care when it happens.