ObjectiveEndoscopic pyloromyotomy (G-POEM) is a minimally invasive treatment option with promising uncontrolled outcome results in patients with gastroparesis.DesignIn this prospective randomised trial, we compared G-POEM with a sham procedure in patients with severe gastroparesis. The primary outcome was the proportion of patients with treatment success (defined as a decrease in the Gastroparesis Cardinal Symptom Index (GCSI) by at least 50%) at 6 months. Patients randomised to the sham group with persistent symptoms were offered cross-over G-POEM.ResultsThe enrolment was stopped after the interim analysis by the Data and Safety Monitoring Board prior to reaching the planned sample of 86 patients. A total of 41 patients (17 diabetic, 13 postsurgical, 11 idiopathic; 46% male) were randomised (21 G-POEM, 20-sham). Treatment success rate was 71% (95% CI 50 to 86) after G-POEM versus 22% (8–47) after sham (p=0.005). Treatment success in patients with diabetic, postsurgical and idiopathic gastroparesis was 89% (95% CI 56 to 98), 50% (18–82) and 67% (30–90) after G-POEM; the corresponding rates in the sham group were 17% (3–57), 29% (7–67) and 20% (3–67).Median gastric retention at 4 hours decreased from 22% (95% CI 17 to 31) to 12% (5–22) after G-POEM and did not change after sham: 26% (18–39) versus 24% (11–35). Twelve patients crossed over to G-POEM with 9 of them (75%) achieving treatment success.ConclusionIn severe gastroparesis, G-POEM is superior to a sham procedure for improving both symptoms and gastric emptying 6 months after the procedure. These results are not entirely conclusive in patients with idiopathic and postsurgical aetiologies.Trial registration numberNCT03356067; ClinicalTrials.gov.