Acute pancreatitis is a rare phenomenon in children but its incidence seems to be increasing. In children, it is generally caused due to systemic illness, biliary disease, trauma, idiopathy and side effects of medicines like L-aspariginase. Acute pancreatitis is difficult to diagnose in children since the clinical presentation is highly variable. Complications such as pseudocysts have been reported at rates as high as 25%. Severe cases of pseudocysts may be further complicated by a possible lethal splenic artery pseudoaneurysm. In this case report, we present a rare case of splenic artery pseudoaneurysm due to acute pancreatitis in a 6-year-old boy with acute lymphoblastic leukaemia treated with L-aspariginase. He presented with fever, irritability and pain in his left groin region.