Thymosin β4 (Tβ4), a 5 kDa protein, has been demonstrated to play an important role in a variety of biological activities, such as actin sequestering, cellular motility, migration, inflammation, and damage repair. Recently, several novel findings provided compelling evidence that Tβ4 played a key role in facilitating tumor metastasis and angiogenesis. It has been found that Tβ4 expressed increasingly in a number of metastatic tumors, which was associated with an increased expression of a known angiogenic factor, vascular endothelial growth factor. Thus, Tβ4 provided a potential target of opportunity for cancer management, especially for cancer metastasis therapy.