AIM: To study the effect of curcumin on the expression of p21 and CD44V6 in breast carcinoma in nude mice.METHODS: Nude mice were xenografted with human breast cancer cell line MCF-7 and randomly divided into 2 groups(n=4 in each group): control group and curcumin group.In latent period,the percentage of tumor development was observed.Tumors were measured and the surface areas were calculated.RT-PCR was performed to detect the expression level of cyclin D1,p21 and CD44V6 mRNA.RESULTS: The tumor surface areas in the curcumin group were significantly lower than those in control group.In curcumin treatment group,the expression of p21 was up-regulated while cyclin D1 was nearly not changed.The expression of CD44V6 was significantly down-regulated in curcumin group.CONCLUSION: Curcumin inhibits the expression of CD44V6 and up-regulates the expression of p21 in nude mice bearing human breast cancer cell line MCF-7.