Between April 1993-September 1995, we studied the activity of adenosine deaminase (ADA) in the peritoneal fluid of 72 patients who were divided into three groups according to causes of ascites, as follows: tuberculous peritonitis (group I), secondary to malignant tumors (group II), cirrhosis of the liver (group III). In tuberculous ascitic fluid, ADA levels were 55.4±7.3 IU/L (mean±SD), which was significantly more than that noted in cirrhotic (7.6±3.9 IU/L), or malignant (15.5±7.7 IU/L) ascitic fluids (P