L-asparaginase is an important component of antileukemic therapy in patients with acute lymphoblastic leukemia. The degree of L-asparaginase toxicity is variable. Several cases of L-asparaginase related pancreatitis have been reported in the literature. However, necrotizing pancreatitis in adult has not been reported yet. Herein, we present a case of necrotizing pancreatitis caused by L-asparaginase that was complicated by pancreatic duct leakage and pseudocyst formation, but successfully treated with percutaneous drainage and octreotide treatment. Korean J Pancreatobiliary 2015;20(4):222-227