Abstract Core B, Tissue Bank provides the infrastructure to transport, receive, process, store, and distribute tissue specimens obtained from patients with myeloproliferative neoplasms (MPN) as well as patients enrolled on clinical trials (Project 4). These specimens are provided to MPN-RC investigators performing translational research for the purpose of developing innovative therapies (Projects1-3) and to the Biomarker & Bioinformatics Core D to perform biomarker analyses to evaluate the effectiveness of specific therapies to deplete MPN hematopoietic stem and progenitor cells (HSC/HPC). Tissues are also available to members of the scientific community at large for translational research. Translational research is dependent on the ready availability of tissues from a sufficient number of accurately diagnosed patients to generate statistically significant data. Because the MPNs are relatively uncommon and their accurate diagnosis can be difficult, there has been a paucity of tissue, linked to clinical data, available to individual investigators at single institutions. Core B fills this void. With an inventory of more than 15000 specimens from more than 1500 individual patients with MPNs, Core B maintains one of the world's largest inventories of MPN tissues available for research. In addition, Core B collects specimens from patients participating in MPN-RC sponsored clinical trials (Project 4) for the purpose of performing biomarker studies to demonstrate the effectiveness of specific therapies on the depletion of MPN hematopoietic stem and progenitor cells (HSC/HPC). The specific aims of Tissue Bank Core B are to: 1) Receive, process, cryopreserve, and store tissues from MPN patients as well as patients enrolled on clinical trials (Project 4) at MPN-RC clinical sites; 2) Provide a central repository for MPN tissues that are associated with basic data stored in the web-based data bank maintained by Biostatistics and Data Management Core C including clinical, and laboratory data that enable selection and distribution of tissues best suited for each translational research project; 3) Distribute tissues to: MPN Consortium investigators for translational research to develop innovative therapies; MPN Consortium investigators to analyze biomarkers to determine therapeutic and pharmacodynamic response to therapy as well as to predict disease progression; and scientific community at large for translational research. Tissues are available to members of the MPN Research Consortium (MPN-RC) and to the scientific community at large for the performance of translational research. Core B is an essential shared resource that enables translational research that will ultimately lead to the development of molecularly targeted therapies.