The α chain of interleukin 3 receptor (IL-3Rα or CD123), together with the common β (βc) subunit, forms a high-affinity IL-3R with biological function. In recent years, emerging research has found that CD123 is highly expressed on the surface of various cells (e.g., leukemia stem cells, LSCs), and it is associated with the initiation and development of many diseases, such as acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). As a novel biological marker, it has an attractive prospect in the diagnosis, targeted therapy, and evaluation of prognosis of many diseases. For these reasons, much attention has been attracted to the studies of the biological functions and potential value in the clinical application of CD123. In this review, the clinical prospects of CD123 will be discussed on the basis of information available.