BACKGROUND:?Hepatocellular carcinoma (HCC) is characte-rized by a multi-cause, multi-stage and multi-focus process of tumor progression. Its prognosis is poor and early diagnosis is of utmost importance. This study was undertaken to investigate the dynamic expression of oncofetal antigen glypican-3 (GPC-3) and GPC-3 mRNA in hepatocarcinogenesis and to explore their early diagnostic value for HCC. METHODS:?A hepatoma model was induced in male Sprague-Dawley rats with 0.05% 2-fluorenylacetamide and confirmed by hematoxylinandeosinstainingandgamma-glutamyltransferase (GGT) expression. Total RNA was purified and transcribed into cDNA by reverse transcription. Fragments of the GPC-3 gene were amplified by nested RT-PCR, and confirmed by sequencing. GPC-3 was analyzed by immunohistochemistry, Western blotting or ELISA. RESULTS:?Positive GPC-3 expression showed as brown granule-like staining localized in the cytoplasm. Histological examination of hepatocytes revealed three morphological stages of granule-like degeneration, atypical hyperplasia (precancerous), and cancer formation, with a progressive increase of liver total RNA and GGT expression. The incidence of liver GPC-3 mRNA and GPC-3, and serum GPC-3 was 100%, 100% and 77.8% in the HCC group, 100%, 100%, and 66.7% in the precancerous group, 83.3%, 83.3%, and 38.9%in the degeneration group, and no expression in the liver or blood of the control group, respectively. There was a positive correlation between liver GPC-3 mRNA and total RNA level (r=0.475, P