Three decades on, the mesenchymal stem cells (MSCs) have been intensively researched on the bench top and used clinically. However, ambiguity still exists in regard to their anatomical locations, identities, functions, and extent of their differentiative abilities. One of the major impediments in the quest of the MSC research has been lack of appropriate in vivo markers. In recent years, this obstacle has been resolved to some degree as PDGFRα emerges as an important mesenchymal stem cell marker. Accumulating lines of evidence are showing that the PDGFRα (+) cells reside in the perivascular locations of many adult interstitium and fulfil the classic concepts of MSCs in vitro and in vivo. PDGFRα has long been recognised for its roles in the mesoderm formation and connective tissue development during the embryogenesis. Current review describes the lines of evidence regarding the role of PDGFRα in morphogenesis and differentiation and its implications for MSC biology.