Four kinds of assays were used to study the effect of a fat-soluble extract of spinach powder(SPFE) on the proliferation of human gastric adenocarcinoma cell line (SGC-7901) in vitro.These studies included: ( i ) cell growth assay, ( ii ) colony forming assay, ( iii ) MTT colorimetric assay, and ( iv ) 3H-TdR incorporation assay. The concentrations of SPFE expressed as the level of β-carotene in the medium were 2 × 10-s, 2 × 10-7 and 2 × 10-6 mol/L β-carotene in assays ( i ) ～ ( iii ), but 4 × 10-8, 4 × 10-7 and 4 × 10-6 mol/L β-carotene in assay ( iV ) respectively. The results indicated that SPFE inhibited the proliferation and colony forming ability of SGC-7901 cells. And in MTT assay, SPFE inhibited the viability of SGC-7901 cells, but no inhibitory effect of SPFE was observed on the viability of lymphocytes in peripheral blood of healthy people. Finally, in the 3H-TdR incorporation test, both SPFE and β-carotene showed significant inhibitory effects on DNA synthesis in SGC-7901 cells, but SPFE was more effective than 3-carotene.