Chylous ascites is an accumulation of lymph in the abdominal cavity. The diagnosis is established when the concentration of triglycerides in plasma is greater than in ascitic fluid over a level of 200 mg/dl. The clinical and biochemical characteristics of 22 patients with chylous ascites (11 cirrhotics and 11 non cirrhotics) were studied in order to assess differences between patients with and without hepatic cirrhosis. The cirrhotic patients with chylous ascites showed lower protein (1.3 +/- 0.74 mg/dl, p = 0.002) and cholesterol concentration (46.0 +/- 45.2 mg/dl, p = 0.02) in ascitic fluid than non cirrhotic patients (3.1 +/- 1.09 mg/dl, and 100.85 +/- 41.7 mg/dl, respectively). In addition, the cellularity in the ascitic fluid was also lower in cirrhotic patients (209.09 +/- 113.96 cel/mm3) versus (831.8 +/- 945.08 cel/mm3; p < 0.05). Four patients (18.18%) presented high adenosine deaminase levels (ADA) in the ascitic fluid in the absence of tuberculous peritonitis. The authors conclude that the biochemical differences observed in the ascitic fluid of the cirrhotic patients with chylous ascites may be explained by a dilutional mechanism due to the combination of "clear" ascites secondary to portal hypertension and chylous ascites. Furthermore, chylous ascites could be the cause of an elevation in ADA in the absence of tuberculous peritonitis.