Tissue microarrays (TMAs) are means of combining tens to hundreds of specimens of tissue onto a single slide for analysis at one time. TMAs are most frequently constructed from paraffin embedded tissue; however, they can be constructed from frozen tissue. The construction of TMAs is flexible, meeting the focused needs of the investigator. A TMA slide can be processed like an ordinary tissue section, and used for histochemical, immunohistochemical staining or in situ hybridization. Combined with automated new image analysis systems, TMAs are a powerful molecular profiling tool. By confirming the findings of microarray experiments or protein arrays, TMAs can be applied systematically to global cellular network analysis within tissue cell. TMAs are commonly used to confirm the results of expression microarrays as well as in the development of diagnostic and prognostics markers for clinical applications. This review will cover recent advancements in technology for the construction and use of TMAs. Because TMAs can be constructed from archival paraffin embedded tissue, they open up the vast archive of patient samples and make them accessible for medical research. TMAs play an ever increasing role in translational medicine, bridging the chasm of discovery at the research bench to the demonstration of clinical utility prior to implementation in patient care.