A one-month and 19-day-old male infant was assisted in the emergency room with poor acceptance of milk associ ated with postprandial fullness and yellowish skin for one day. On physical examination, he was malnourished, icteric (+++/4+), with no palpable masses in the abdomen. Laboratory tests showed high values of alkaline phosphatase (226U/l), gamma-glutamyl transferase (646 U/l) and bilirubin (8.5 mg/dl - 6.0 mg/dl direct and 2.5 mg/dl indirect). The ultrasound performed in the intensive care unit (ICU) showed a Todani classification I choledochal cyst (Fig. 1). Magnetic cholangioresonance confirmed the finding (Fig. 2). The two exams did not detect renal anomalies. The newborn was discharged from ICU after 7 days of hospitalization, and operated by laparotomy 20 days later, with satisfactory results after cholecystectomy and reconstruction by Roux-en-Y hepaticojejunostomy. Hepaticojejunostomy and laparoscopic open cyst excision seem to be efficacious and secure with intraoperative and postoperative results that are enhanced to those of open excision in the set of children with choledochal cysts. It´s noteworthy that the risk of malignant transformation of this disease increases with age, reaching 11.4% above 20 years of age. Unoper ated cases may progress to complete biliary obstruction, secondary biliary cirrhosis, cholangiocarcinoma, and septic cholangitis due to severe infection.