Achalasia is a rare oesophageal motility disorder which classically is not associated with obesity. We present the case of a 50-year-old woman who underwent gastric bypass and afterwards was diagnosed with achalasia. Following, she was treated successfully with peroral endoscopic myotomy (POEM). A thorough medical history revealed that symptoms of achalasia had been present for 25 years and were the cause of inappropriate eating habits and consequently morbid obesity. This case story illustrates the importance of being aware of simultaneous occurrence of achalasia and morbid obesity. Furthermore, it demonstrates that POEM is safe and effective for symptomatic relief of achalasia after previous gastric bypass.