Introduction: Choledochal cyst is an uncommon congenital anomaly of Hepoatobiliary system. It is a case of choledocal cyst presenting as perforation and biliary ascites which is rare in infants. Clinical picture: An infant was admitted at BLDE hospital with history of convulsion and breathlessness, on examination child had abdominal distension. Investigations like erect X ray abdomen done which revealed ascites with features of peritonitis, so exploratory laparotomy done which showed a choledochal cyst with perforation causing biliary ascites. Treatment: Child was treated in the pediatric intensive care unit for convulsion. Exploratory laparotomy done and the perforated choledochal cyst was sutured and drain placed in situ. The child improved from 2nd post operative day. Conclusion: Choledochal cyst can present as perforation, biliary ascites and peritonitis in infants. Therefore treatment should be oriented to this aspect also.