Choledochal cysts are uncommon congenital anomalies of the biliary tree, commonly presenting in infancy, generally in the 1^st year of life. Presentation in adult life is less common, accounting for 20% of cases. A 19-year-old female patient presented to the Emergency Department with severe abdominal distension, a palpable abdominal mass, mild jaundice and low grade fever. Ultrasound, computed tomography (CT) and magnetic resonance imaging of the abdomen showed a massive septated cystic lesion filling the entire abdomen with a significant mass effect on surrounding structures. Origin of the lesion was unclear and diagnosis included a giant mesenteric or duplication cyst, massive gallbladder with hydrops, biliary cystadenoma and giant choledochal cyst, among others. Final diagnosis was a Type IA choledochal cyst with massive asymmetric cystic dilatation of the extra-hepatic segments of the left hepatic duct with asymmetric dilatation of the right hepatic duct. Patient had an uneventful recovery after resection of the entire extrahepatic cyst and Roux-en-Y hepaticojejunostomy at the level of the hilum. In this article, we correlate CT and MRI findings to gross and histopathological findings of this giant Todani's Type IA choledochal cyst.