Using curcumol that was extracted from the volatile oil of Rhizoma Curcumae as the raw material, its derivatives were synthesized and purified. The structures of these compounds were confirmed by (1)H, (13)C NMR, and mass spectral data. The test compounds were evaluated for their in vitro anti-tumor activity against gastric cancer cell lines SGC-7901 and lung carcinoma cell line H460 by methyl thiazolyl tetrazolium chromatometry. Distinct structure-activity relationships of these curcumol derivatives were also revealed for inhibiting cell proliferation. Presence of electron-withdrawing groups or amino could increase the activity significantly, whereas esterification of 8-hydroxy diminished the anti-tumor activity. Many of the tested candidates exhibited higher inhibition efficiency than curcumol, suggesting that structural modifications could enhance its activity effectively.