Using fecal alpha-1-antitrypsin (FA-1-AT) as an endogenous marker of enteric protein loss, measurements on random non-dried stool samples were carried out in 20 normal healthy subjects and 30 patients with schistosomal hepatic fibrosis (SHF); 12 of them had intestinal polyposis (IP) and better hepatic functions than the others. FA-1-AT concentrations were significantly higher in schistosomal patients with or without IP than in normal subjects. Excluding those with IP, increased enteric protein loss was detected in 11 patients (61.1%) with SHF and there were definite relationship between FA-1-AT concentration and serum albumin level (r = 0.475), prothrombin activity (r = -0.625), Child-Pugh score (r = 0.614) and the presence of ascites. On the other hand, patients with IP had significantly higher FA-1-AT concentration and serum albumin level than other schistosomal patients. This excessive enteric protein loss did not correlate with serum albumin level or severity of liver disease. The cause-and-effect relationship between enteric protein loss and hypoalbuminemia has been discussed in the light of these findings. It can be concluded that protein-losing enteropathy (PLE) in patients with SHF appears to represent a paraphenomenon associated with the progress of liver disease and only becomes of major clinical significance when the hepatic synthetic activity is compromised. Determination of FA-1-AT concentration proved to be an inexpensive, rapid, convenient, nonisotopic screening test that eases diagnosis of PLE.