AIM To reveal the inhibitory effects of Curcuma aromatica oil ( CAO ) on cell proliferation of hepatoma in mice.METHODS Two tumor inhibitory experiments of CAO on hepatoma in mice were conducted.The inhibitory effects of CAO on proliferation of hepatoma in mice were evaluated by DNA image cytometry and immunohistochemical staining of proliferating cell nuclear antigen (PCNA).RESULTS The tumor inhibitory rates of CAO were 52% and 51% in two experiments,respectively. Compared with those of the salinetreated control groups, both differences were statistically significant (P ＜ 0.01). In the group of mice treated with CAO, the cellular nuclear DNA OD value (249 ± 70), areas (623μnm2 ±228 μm2) and DNA (2.38 ± 0.67) index of hepatic carcinomas were significantly lower than those of the control group (430 ± 160, 1073μm2 ± 101 um2 and 4.48 ± 0.71 ). CAO also could increase diploidy cell rates (29.00% ± 9.34% vs 2.97% ± 5.69%, P＜0.01 ) and decrease pentaploidy cell exceeding rate (30.04% ± 15.10% vs 70.89%±14.94%, P＜0.01). In the group of mice treated with CAO, the labeling indexes of proliferating cell nuclear antigen (PCNA-LI) were 30% ± 4%, which were significantly lower than 40% ± 6% of the control group (P＜0.01).CONCLUSION The inhibition of CAO on the growth of hepatoma in mice might be associated with its depression on cellular proliferative activity.