We report a case of acute chylous ascites formation presenting as peritonitis(acute chylous peritonitis) in a patient suffering from acute pancreatitis due to hypertriglyceridemia and alcohol abuse.The development of chylous ascites is usually a chronic process mostly involving malignancy,trauma or surgery,and symptoms arise as a result of progressive abdominal distention.However,when accumulation of “chyle” occurs rapidly,the patient may present with signs of peritonitis.Preoperative diagnosis is difficult since the clinical picture usually suggests hollow organ perforation,appendicitis or visceral ischemia.Less than 100 cases of acute chylous peritonitis have been reported.Pancreatitis is a rare cause of chyloperitoneum and in almost all of the cases chylous ascites is discovered some days(or even weeks) after the onset of symptoms of pancreatitis.This is the second case in the literature where the patient presented with acute chylous peritonitis due to acute pancreatitis,and the presence of chyle within the abdominal cavity was discovered simultaneously with the establishment of the diagnosis of pancreatitis.The patient underwent an exploratory laparotomy for suspected perforated duodenal ulcer,since,due to hypertriglyceridemia,serum amylase values appeared within the normal range.Moreover,abdominal computed tomography imaging was not diagnostic for pancreatitis.Following abdominal lavage and drainage,the patient was successfully treated with total parenteral nutrition and octreotide. We report a case of acute chylous ascites formation presenting as peritonitis (acute chylous peritonitis) in a patient suffering from acute pancreatitis due to hypertriglyceridemia and alcohol abuse. Development of chylous ascites is usually a chronic process mostly involving malignancy, trauma or surgery, and essentials diagnosis is difficult since the clinical picture usually suggests hollow organ perforation, appendicitis or visceral ischemia .Less than 100 cases of acute chylous peritonitis have been reported. Pancreatitis is a rare cause of chyloperitoneum and in almost all of the cases chylous ascites is discovered some days (or even weeks) after the onset of symptoms of pancreatitis. This is the second case in the literature where the patient presented with acute chylous peritonitis due to acute pancreatitis, and the p resence of chyle within the abdominal cavity was discovered simultaneously with the establishment of the diagnosis of pancreatitis.The patient underwent an exploratory laparotomy for suspected perforated duodenal ulcer, since, due to hypertriglyceridemia, serum amylase values ​​have within the normal range .Moreover, abdominal computed tomography imaging was not diagnostic for pancreatitis. Floating abdominal lavage and drainage, the patient was successfully treated with total parenteral nutrition and octreotide.