Background: Hypertriglyceridemia (HTG) is the most common etiology of acute pancreatitis (AP) after alcohol and gallstone-induced disease. Elevation of serum triglyceride (TG) levels to >= 1000 mg/dl in a patient with AP strongly indicates HTG as the cause. The absolute risk of pancreatitis based on serum TG <= 1000 mg/dl has not been clearly defined. The aims of this study were to address the role of elevated TG levels between 500 and 1000 mg/dl in the clinical course of HTG pancreatitis (HTGP); and assess the relationship between the level of serum TG and disease severity. Methods: A total of 224 HTGP patients between 2007 and 2011 were divided into two subgroups. Totally, 122 patients in Group A had serum TG > 1000 mg/dl; 102 patients in Group B had maximal TG levels between 500 and 1000 mg/dl accompanied by lactescent serum; 100 patients with biliary AP and 99 patients with alcoholic AP hospitalized during the study period were enrolled as controls. The clinical and biochemical data were analyzed. Results: The clinical presentation of HTG-induced pancreatitis was similar to other causes. Severe form of AP in Group A was higher than Group B (chi(2) = 4.002, P = 0.045). The severity with HTGP was significantly higher as compared to biliary AP (chi(2) = 33.533, P = 0.000) and alcoholic AP (chi(2) = 7.179, P = 0.007). Systemic complications with HTGP were significantly higher than biliary AP (chi(2) = 58.763, P = 0.000). Conclusions: The study demonstrated that TG level = 500 mg/dl should raise a high degree of suspicion, especially if no other etiology of AP is apparent. The severity of HTGP seems to correlate directly with TG level. HTGP seems be more severe than other causes of AP.