As part of an investigation of the possible role of autoimmune mechanisms in the development of chronic active hepatitis (CAH) in schistosomiasis, sera from 25 patients (Group I) with hepatic schistosomiasis without histological features of CAH and 5 patients (Group II) with CAH and intestinal mansoniasis, but without discernible hepatic infection, were examined for the presence of the liver membrane antibody (LMA) that is reportedly associated with the autoimmune variant of CAH. All patients were HBsAg-negative. Circulating LMA was found in 17 (68%) Group I and 3 (60%) Group II patients. Low titres of various organ-non-specific autoantibodies were found in about a third of all patients but these did not correlate with the presence of LMA. There was also no correlation between LMA and antibodies to the hepatitis B core antigen (anti-HBc), found in the sera of 67% of the patients, indicating that occult or recent past hepatitis B virus infection was not a factor in LMA production. Long-term follow-up of the Group I patients should reveal whether current LMA-positivity is related to eventual development of CAH in hepatic schistosomiasis.