BACKGROUND: Pancreatic extracorporeal shock wave lithotripsy (P-ESWL) is the first-line therapy for large pancreatic duct stones. Although it is a highly effective and safe procedure for the fragmentation of pancreatic stones, it is still not complication-free. Just like endoscopic retrograde cholangiopancreatography (ERCP), pancreatitis is the most common complication. To date, nonsteroidal anti-inflammatory drugs (NSAIDs) have proven to be the only effective prophylactic medication for post-ERCP pancreatitis and the European, American and Japanese Society for Gastrointestinal Endoscopy guidelines have recommended prophylactic rectally administered indomethacin for all patients undergoing ERCP. Given the little research about effective prevention for post P-ESWL pancreatitis, we aim to determine whether rectally administered indomethacin can reduce post-ESWL-pancreatitis. METHODS/DESIGN: The RIPEP study is a prospective, randomized, double-blinded, placebo-controlled trial. One thousand three hundred and seventy patients with chronic pancreatitis and pancreatic stones (>5 mm in diameter) treated with P-ESWL at Changhai Hospital will be randomly allocated to rectally administered indomethacin or placebo therapy before the procedure. The primary endpoint is the incidence of post-ESWL pancreatitis. Secondary endpoints include the severity of pancreatitis, occurrence rate of asymptomatic hyperamylasemia and other complications. DISCUSSION: The RIPEP trial is designed to show that rectally administered indomethacin reduces the development and severity of post-ESWL pancreatitis and benefits patients treated with P-ESWL. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT02797067 . Registered on 17 November 2016.