Objectives Acute cholecystitis commonly occurs in elderly patients who are at high-risk for surgery. Whether upfront Endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) is advantageous over antibiotics first for mild acute cholecystitis is uncertain. Hypothesis to be tested The aim is to compare EUS-GBD versus standard protocol (antibiotics first) as a definitive treatment, in very high-risk patients suffering from mild to moderate acute cholecystitis. We hypothesize that EUS-GBD can reduce the 1-year risk of recurrent acute cholecystitis. Design and subjects This is an international randomised controlled study including consecutive patients suffering from acute cholecystitis that are very high-risk for cholecystectomy. The patients would be randomized to receive EUS-GBD or antibiotics first. Interventions: EUS-GBD versus antibiotics Main outcome measures: The primary outcome is the rate of recurrent acute cholecystitis in 1 year. Other outcomes include technical and clinical success, post-procedural pain scores, analgesic requirements, adverse events, re-admissions, re-interventions, quality of life and cost analysis. Data analysis All outcomes would be analysed according to the intention-to-treat principle. Kaplan-Meier method with the log-rank test will be used to compare differences in recurrent acute cholecystitis in 1 year. A health economic analysis will also be performed. Assuming a 17.1% difference in recurrent acute cholecystitis rates, a 2-sided P value of 0.05, a power of 80%, and a 10% dropout rate, 110 patients is required. Expected results The findings of this study can help establish the role of EUS-GBD in management of high-risk patients suffering from acute cholecystitis over antibiotics alone and Percutaneous transhepatic gallbladder drainage.