OBJECTIVE : Congenital chylous ascites (CCA) is a rare disease, caused by abnormality of the intra-abdominal lymphatic system, and no gold standard treatment. It is defined as the accumulation of triglyceride-rich milky fluid into peritoneal cavity. The incidence of chylous ascites is reported 1:20.000 – 1:187.000 every live births.
CASE : Young male infant was accidentally diagnosed with congenital ascites in 6 month pregnancies, history of preterm labor on 7 month pregnancies, then the patient hospitalized in high risk neonatal ward for 15 days. After hospitalized, patient has regularly visited outpatient department of surgery and pediatric at the local hospital. The complaint was abdominal enlargement due to ascites. Because no improvement obtained during treatment, patient was referred to Dr. Kariadi Hospital. In Dr. Kariadi Hospital patient have been checked for TORCH serology with negative result and treated with propanolol for 2 weeks, but the complaint was not improved. At 7 month (chronological) age, patient undergo a percutaneus abdominal drainage with unsatisfied result. Ascites examination result, milky and cloudy liquid, positive result of Rivalta test, normal protein count, high level of leucocyte count. The microbiological examination revealed no bacteria, negative yeast cell, negative for BTA and leucocyte count 1-5 field of view. Then laparotomy was performed and  revealed no abnormalities in abdominal cavity. After exploratory laparotomy, ascites has been diminished and patient condition improved. Abnormalities in this disease connected with the development and maturation of lymphatic vessels. Because this is a rare disease, diagnose and therapy was difficult to conduct. Abdominal paracentesis is important to diagnosed this disease. 
CONCLUSION : In the newborn with congenital ascites, congenital chylous ascites has become one of our consideration. If oral therapy ineffective, surgical treatment like exploratory laparotomy could be an option.