Sixty-one patients (1 to 18 1/2 years of age) with acute pancreatitis were evaluated. In over one third of cases, acute pancreatitis was one feature of a multisystem disease (Reye syndrome, sepsis, shock, hemolytic-uremic syndrome, viral infections). Other common causes included blunt trauma (15%), acquired or congenital structural defects (10%), metabolic diseases (10%), and drug toxicity (3%). In 25% of cases, no cause was identified. All conscious patients complained of abdominal pain, but the location, severity, and duration of pain were extremely variable. Vomiting was a common symptom. Ultrasonography was helpful in establishing the diagnosis and for assessment of complications such as pseudocyst formation. Endoscopic retrograde cholangiopancreatography was used to identify structural or anatomic lesions in patients with recurrent acute pancreatitis. Serum cationic trypsin(ogen) was superior to amylase in the early diagnosis of acute pancreatitis, and was more consistently elevated during the first 5 days in the hospital. Patients were managed conservatively with complete bowel rest, gastric decompression, intravenous fluid therapy, and pain relief. Pancreatic pseudocysts occurred in 10% of patients. There were 13 fatalities, all in patients with a severe multisystem disorder. Recurrences of acute pancreatitis were noted only in certain diagnostic groups: idiopathic pancreatitis, structural anomalies of the pancreaticobiliary tree, metabolic disorders, and (in a single patient) familial pancreatitis.