Introduction: Chylous ascites (CA) is an uncommon cause of undifferentiated abdominal pain, with an estimated incidence of 1 in 20 000. Idiopathic CA is rarer still, with limited evidence on management. We present a case of idiopathic acute chylous peritonitis, its multidisciplinary diagnostic evaluation, and the outcome over a 8-month period of follow-up. Case Description: A 48-year old female presented with abdominal pain and vomiting. Exam revealed peritonitis and abdominal distention with a WCC of 16.7x109 /L. A CT-scan of the abdomen suggested unusual distribution of small bowel and free fluid. A diagnostic laparoscopy to exclude an internal hernia demonstrated four quadrant CA without any bowel obstruction or obvious retroperitoneal pathology. Operative drainage, total parenteral nutrition and empirical antibiotics with gradual diet upgrade resulted in uncomplicated recovery. Tumour markers, infectious serology and immunological investigations along with fluid cytology, electrophoresis and flow cytometry were unremarkable. Lymphangiography demonstrated no leakage of lymph in the chest, abdomen or, retroperitoneum. FDG-PET performed three months later did not demonstrate any uptake to raise concern for an infectious or malignant process Serial follow-up till 8 months showed complete resolution of symptoms. Discussion: The diagnosis of CA is made when there is an accumulation of milky white, triglyceride-rich intraperitoneal fluid. Investigations should be directed at ascertaining the underlying cause of lymph leakage through systematic workup. In adults, causes may include malignancy, infection, and trauma. Multidisciplinary input and long term follow-up is required prior to diagnosis of idiopathic CA.