Twenty-eight cases of chylous ascites occurring over the past 20 years are analyzed for clinical presentation, cause, yield of diagnostic procedure used, and response to therapy. Malignancies were responsible for 21 of 24 adult cases of chyloperitoneum, with lymphomas predominating (13 cases). The dismal prognosis in adult cases (12 patients died within 3 months) shows the need for appropriate diagnostic assessment including early lymph node biopsy or laparotomy, or both, when indicated. Surgery, chemotherapy, or radiation therapy should be instituted promptly except in cases resulting from surgical trauma to lymphatics, which frequently resolve with conservative management. Three of the four pediatric cases of chylous ascites resulted from congenital lymphatic anomalies; the fourth case resulted from operative trauma. Aggressive diagnostic and therapeutic interventions are not warranted in childhood cases of chylous ascites until conservative management (paracentesis, low-fat diet, medium-chain triglyceride supplementation) has failed; neoplasia is rarely implicated and many cases resolve within a few months.