The protein-tyrosine phosphatase (PTP) CD45 serves both positive and negative signaling elements by dephosphorylating regulatory pTyr residues on Srcfamily protein-tyrosine kinases. Although its physiological participation in immune function makes it an important point of intervention for treatment of a variety of inflammatory and immune disorders, comparatively little has been reported on development of CD45 inhibitors. Frequently, when inhibitory data against CD45 is reported, the data has been generated secondarily to other target PTPs. The focus of the current review is to summarize the types of structures that have been found to inhibit CD45, even in cases the compounds themselves were designed as antagonists of other PTPs. The reviews organization begins with generic broad spectrum PTP inhibitors and progresses from peptide-based inhibitors and small molecule peptide mimetics to inhibitors that have resulted from screening hits. Although potent and moderately selective CD45 inhibitors have been reported, no single dominant theme has yet emerged in the design of these CD45-directed agents.