Here we present 3 cases of childhood-onset autoimmune pancreatitis: 2 cases in boys aged 4 and 16 years, diagnosed with ulcerative colitis; 1 case in a previously healthy 10-year-old boy. All 3 boys presented with abdominal pain associated with elevated pancreatic enzyme levels. Immunoglobulin G4 levels were elevated only in the 16-year-old boy. However, pancreatic enlargement together with narrowing of the main pancreatic duct was evident on computed tomography in all 3 cases. Autoimmune pancreatitis is an uncommon disease in childhood, and only 3 cases affecting patients under 17 years of age have previously been reported in Japan. Autoimmune pancreatitis may be latent in children with pancreatitis who have chronic or intermittent abdominal symptoms. In addition, it is necessary to recognize autoimmune pancreatitis as a complication of pediatric inflammatory bowel disease. The clinical features of pediatric autoimmune pancreatitis remain unclear, and an accumulation of cases is necessary.