As a family of chromatin remodeling proteins, metastasis-associated proteins (MTAs) have shown to be the master regulators in both physiological and pathological contexts. Although MTA3 is the latest being identified in MTA family, it has started to draw as much attention as the other family members. MTA3 is expressed in various tissues and is associated with different physiological functions. In cancerous context, both MTA1 and MTA2 are generally considered as oncogenes because they are capable of enhancing metastasis. However, MTA3 appears to play more complicated roles in cancers depending on the contexts. As a tumor suppressor, MTA3 usually down-regulates Snail, the master regulator of epithelium-mesenchymal transition, and subsequently represses cancer cell invasion and migration. Additionally, MTA3 may function by enhancing cancer cell differentiation without affecting proliferation in certain cancers. On the other hand, MTA3 might function in oncogene - related properties similarly as MTA1 and MTA2. In this review, we summarize our current understanding about MTA3 in normal development, cancers as well as other human diseases by comparing the similarities and differences between MTA3 and the other members of the MTA family.