Myelofibrosis is a rare bone marrow malignancy. It is classed as a myeloproliferative neoplasm whereby there is clonal proliferation of hematopoietic stem cells in the bone marrow resulting in fibrosis. It can present as a primary disease or evolve from polycythemia vera or essential thrombocythemia. Median survival is 2 to greater than 15 years depending on prognostic factors. The JAK2V617F mutation is the most common abnormality in myeloproliferative neoplasms. Dysregulation in the JAK signalling pathway is often seen in patients who have myelofibrosis. Thus, there has been intense focus on selective JAK2 inhibition in terms of targeted drug therapy.