Background and Study Aims Endoscopic biliary drainage is an established mode of treatment for acute cholangitis. We compared the safety and efficacy of 7 Fr and 10 Fr stent placement for biliary drainage in patients with acute cholangitis. Patients and Methods We recruited 40 patients with severe cholangitis who required endoscopic biliary drainage. Patients were randomized to have either a 7 Fr or a 10 Fr straight flap stent placement during endoscopy. Outcome measures included complications related to endoscopic retrograde cholangiopancreatography (ERCP) and clinical outcome. Results Of 40 patients, 20 were randomized to the 7 Fr stent group and 20 to the 10 Fr stent group. All patients had biliary obstruction due to stones in the common bile duct. Indications for biliary drainage were: fever > 100.4A degrees F (n = 27), hypotension (n = 6), peritonism (n = 10), impaired consciousness (n = 8), and failure to improve with conservative management (n = 13). Biliary drainage was achieved in all patients. Abdominal pain, fever, jaundice, hypotension, peritonism, and altered sensorium improved after a median period of 3 days in both groups. Leukocyte counts became normal after a median time of 4 days in the 7 Fr stent group and 6 days in the 10 Fr stent group. There were no ERCP-related complications. There were no instances of occlusion or migration of stent. The success rates of biliary drainage in cholangitis were not affected by the size of stent used. Conclusions Biliary drainage by 7 Fr stent or 10 Fr stent is equally safe and effective treatment for patients with severe cholangitis.