Evidences from epidemiology and experimental oncology have demonstrated that selenium exhibits apparently inhibitory effects on the viral and chemi-cal carcinogenesis, the growth of cultured tumor cells and transplantable carcinomas. The mechanism of selen-(?)m effects were accumulated in a decade of years at cellular and metabolic levels including influence on the membrane—bound, signal systems, and reversion of a few pairs of parameters involved in cell proliferation and differentiation, and the cellular reversion of cultured hepatoma and pulmonary adenocarcinoma cells. However, it is still deficient in cogent experimental data to verify the behavour of selenium on the modulation of cell proliferation and differentiation.This dissertation through the studying the effects of seleni(?) on the relationship between the expre(?)sion of p(?)cliferation-associated and differentiation-as(?)ciated genes in mouse hepato(?)a ascites cells in