Periostin is a newly identified mesenchyme-specific gene encoding a protein of 835 amino acids, with a molecular size about 90 000. Periostin can promote proliferation and differentiation of osteoblasts, recruitment and attachment of osteoblast precursors, and migration of stromal smooth muscle cells. Periostin can be found in many normal tissues in humans, and it is over-expressed in lung caner, colon cancer, liver cancer, esophagus cancer, breast cancer, ovarian cancer, and so on. Periostin can promote neoplasm growth and angiogenesis and may serve as a biomarker of epithelial-mesenchymal transition (EMT). Moreover, the role of periostin in cancer invasion and metastasis is gaining increasing attention and has yielded some progress.