Objectives : The Purpose of this study was to identify anti-tumor effects of Curcuma longa L. on some kinds of cancer cells through molecular biologic methods. Materials & Methods : We used 4 kinds of cancer cell lines such as glioma cells(A172), cervical cancer cells(HeLa), Prostate cancer cells(PC3), lung cancer cells(A549). We injected the boiled extract of Curcuma longa L. $5{mu}g,;10{mu}g$ to culture media(ml) for 24 hours. We measured the cytotoxic effect on 4 kinds of cancer cells through trypan blue exclusion test and the suppressive effect on viability of 4 kinds of cancer cells via MTT assay. We measured the change of mitochondria membrane potential via flow cytometry. The quantitative RT-PCR was used to examine the effect on the revelation of Bcl-2 and Bax which genes are related to apoptosis. We examined the effect on the revelation of Bcl-2 protein and Bax protein by western blot analysis. Results: 1. Extract of Curcuma longa L. showed significant cytotoxic effect on A172, HeLa, PC3 compared to the control group with density dependent manner. 2. Extract of Curcuma longs L. showed significant suppressive effect on viability of A172, HeLa, PC3 compared to the control group with density dependent manner. 3. Curcuma longs L. induced apoptosis by decreasing the membrane potential of mitochondria in A172, HeLa, PC3. 4. In the test about the revelation of genes related to apoptosis, the revelation of Bcl-2 decreased and the revelation of Bax increased in A172. HeLa, PC3 treated with Curcuma longa L. with density dependent manner. 5. In the test about the revelation of protein related to apoptosis, the protein levels of Bcl-2 decreased and the protein levels of Bax increased in A172, HeLa, PC3 treated with Curcuma longa L. Conclusions: This experiment shewed that Curcuma longs L. has anti-tumor effect on glioma, cervical, Prostate cancer cells except on lung cancer. We hope that anti-tumor effects of Curcuma longa L. will be more Practically identified.