A lot of investigations showed that alpha-fetoprotein(AFP) could regulate the proliferation of tumors or neoplastic cells. In order to study the enhancement of this function, AFP was extracted from human cord blood serum and was allowed to act on HeLa cell in vitro. The cellular proliferation was investigated by using the MTT assay and the [(3)H]-incorporation, and the cell cycle was analysed with flow cytometry. Radioactive immunosorbent assay was utilized to detect cAMP accumulation, protein kinase A activity and confocal microscopy was used f or scanning intracellular calcium. The expression of mutant p53 and p21(ras) protein were analyzed by Western blotting. Our results showed that AFP (>10 mg/L ) had strong effect of enhancement on the proliferation of HeLa cells; AFP (20 mg /L) could significantly increase the concentration of cAMP (300%), Ca(2+) (154.9%) and protein kinase A activity (100%). It was also shown that the expression of mutant p53 and p21(ras) protein of HeLa cells were enhanced after t he treatment with AFP (20 mg/L) for 24 hours. Compared with control, the expression of mutant p53 protein was increased by 81.1% (24 h), p21(ras) protein was increased by 96.2% (24 h) respectively; but the monoclonal antibody to AFP blocked these functions of AFP. In conclusion, AFP enhanced the proliferation of HeLa cells; AFP may regulate the growth of the cells by influencing the transmembrane signal pathway and enhancing the expression of the oncogenes.