Agenesis of the dorsal pancreas is a rare congenital pancreatic malformation. We herein describe a 67-year-old woman with a 5-day history of lower back pain who was eventually diagnosed with agenesis of the dorsal pancreas. Abdominal computed tomography showed an enlarged pancreatic head, but the pancreatic body and tail were invisible. The magnetic resonance imaging findings were similar to the computed tomography findings. Magnetic resonance cholangiopancreatography showed that the major pancreatic duct was mildly dilated but otherwise normal. Endoscopic ultrasound revealed absence of the pancreatic body and tail, an enlarged head of the pancreas, and mild pancreatic duct dilation. The final diagnosis was dorsal pancreatic agenesis.