The actual interest of immunoscintigraphy for the detection of liver tumours was investigated by both visual examination and quantitative analysis in 41 patients with hepatoma (HCC, 21 cases, 13 AFP-secreting), other primary or secondary liver cancer (9 cases), testicular cancer (2 cases) and cancer free cirrhosis (9 cases). All patients were injected with 123I-anti-alphafetoprotein (AFP) monoclonal antibodies (MAbs) and scans were performed after 28 +/- 2 h. In the hepatoma-bearing patients, 11 positive anti AFP scans were found; 9 of them had an enhanced serum; besides, 3 non HCC tumours were also detected. With respect to hepatoma diagnosis, sensitivity was 52.5% and specificity 66.5%. For all hepatomas, it was striking that the positivity rate was 2/10 and 9/11, respectively, when HCC was and was not associated with cirrhosis. Among 6 patients with a positive anti AFP scan who were also injected with control anti hCG 123I-MAb, 5 positive anti hCG scans were surprisingly found, with specificity indices ranging between 1.00 and 1.75. The quantitative study also highlighted the importance for hepatoma detection of specific and non specific factors such as serum AFP, tumoural vascularization, non tumoural liver uptake and intrahepatic distribution of HCC. Anti AFP immunoscintigraphy appears as a poorly sensitive and moderately specific method for hepatoma diagnosis. In contrast, non tumoural liver uptake level could be more useful for discriminating HCC from liver metastases and perhaps to detect the early extension of HCC.