Thrombopoietin (Tpo) is a highly conserved cytokine that regulates haematopoiesis. The thrombopoietin receptor (TpoR) is a homodimeric Type1 I transmembrane receptor that upon binding to Tpo, initiates downstream signalling pathways most notably through the JAK-STAT and MAPK/ERK pathways, regulating the maintenance of hematopoetic stem cells, as well as production of megakaryocykes (platelet-producing cells). Dysregulation of Tpo signalling has been linked to various hematological disorders, such as thrombocytopenia (lack of platelets due to reduced Tpo signalling) and myeloproliferative neoplasms (due to excess signalling). TpoR agonists such as Romiplostim are critical in the therapeutic treatment of thrombocytopenia, by stimulating platelet production. However the structural details of how Romiplostim engages the TpoR remain unknown. We have previously solved the structure of Tpo in complex with TpoR by cryo-electron microscopy (cryo-EM) and we now aim to use cryo-EM to provide atomic resolution details of the interaction between Romiplostim and TpoR. Understanding the molecular structure of TpoR and its interaction with Romiplostim will provide the information required for improved therapeutics to treat thrombocytopenia.