Abstract: BACKGROUND AND AIM：To explore the mechanisms of Reinforcing Qi and Nourishing Yin in inhibiting tumor metastasis. MATERIALS AND METHODS：By duplicating spontaneously metastazing tumor model, the changes of the tumor cell phenotype were studied. Total RNA of tumor tissues was extracted, and fluorescent cDNA probes were prepared through reverse transcription of the isolated mRNAs. The RNA samples were labeled with Cy3-dUTP or Cy5-dUTP, then hybridized with microarrays and the chips were scanned with a ScanArray. The acquired images were analyzed using GenePixPro 3.0 software. RESULTS：Reinforcing Qi and Nourishing Yin could inhibit spontaneous tumor metastasis.Gene expression spectrum revealed that it could regulate multiple target genes such as tumor filtration and metastasis，signal transduction，cell proliferation，apoptosis and metabolism-related genes. CONCLUSION：Reinforcing Qi and Nourishing Yin had effects on anti-tumor metastasis. cDNA microarrays technology may be powerful tools in discovering the possible mechanisms of drug at the gene level, and provides new information for further research.

Key words: Reinforcing Qi and Nourishing Yin, neoplasm transplantation, gene expression profiles