A 10-year-old girl developed L-asparaginase (ASP)-associated pancreatitis during chemotherapy for acute lymphocytic leukemia. Her symptoms showed alleviation with continuous regional arterial infusion of protease inhibitor and systemic somatostatin analog therapy. She had intermittent and marked hypertriglyceridemia, an initial trigger for pancreatitis, probably as a side effect of ASP and steroids. However, we considered the pancreatitis to have developed mainly because of factors other than hypertriglyceridemia as lipoprotein analysis confirmed chylomicron levels to be nearly undetectable. Extremely large chylomicrons contribute directly to the onset of pancreatitis by causing blockage of small vessels. Although it is necessary to examine patients for dyslipidemia developing as a side effect of ASP, therapeutic intervention for hypertriglyceridemia is not considered to prevent the onset of ASP-associated pancreatitis.