Hypertriglyceridaemia is thought to be the aetiology in 3% of patients with acute pancreatitis, often associated with poorly controlled diabetes mellitus or chronic alcohol abuse. However, in patients with non-biliary pancreatitis, chylomicronaemia is an underrated cause of acute pancreatitis. The activity of lipoprotein lipase (LPL) is crucial in removing triglycerides from the plasma; LPL gene mutations combined with secondary alterations in plasma lipoproteins, such as occur in pregnancy, diabetes mellitus, and alcohol abuse can cause severe hypertriglyceridaemia and pancreatitis. Heparin and insulin stimulate LPL activity. During a 12 months' period we consecutively screened all patients with the diagnosis of acute non-biliary pancreatitis for hypertriglyceridaemia, to evaluate the prevalence of hypertriglyceridaemia-induced pancreatitis and to assess the outcome under standardised treatment with intravenous heparin and insulin. Hypertriglyceridaemia-induced pancreatitis was diagnosed in 5 out of 46 patients (11%) with acute pancreatitis. In 2 patients hypertriglyceridaemia was associated with diabetes mellitus, in one patient with pregnancy and in another with chronic alcohol abuse. Four patients had to be referred to the intensive care unit. Plasma concentrations of triglycerides were (median +/- range) 43 mmol/l (14.7 to 80.4); pancreas amylase was 574 U/l (155 to 1606), and lipase was 1003 U/l (330 to 3010). All patients had oedematous pancreatitis demonstrated by CT scan. Treatment with i.v. heparin and i.v. insulin decreased trigylceride levels to less than 10 mmol/l within 2.8 days (1 to 6), the amylase and lipase levels returned to normal after 3 and 4 days respectively, and the abdominal pain was resolved. Hypertriglyceridaemia is a common and under-diagnosed etiology of acute non-biliary pancreatitis. Intravenous heparin and insulin is safe and effective in the treatment of hypertriglyceridaemia-induced pancreatitis. Low fat diet, supplements of (n-3) fatty acids ("fish oil") and fibrates are recommended for long-term maintenance therapy.