The myeloproliferative neoplasms are a group of clonal stem cell disorders with similarities at the phenotypic and molecular level. Clinically, these disorders are characterised by over-production of one or more mature myeloid elements and a variable tendency to develop acute myeloid leukaemia. Polycythaemia vera, essential thrombocythaemia and primary myelofibrosis overlap clinically and with their morphological features. In this presentation the blood film appearances as well as the bone marrow morphology of the major myeloproliferative neoplasms, as classified by the WHO, will be presented. This will include the chronic as well as the progressive phases (leukaemic and fibrotic) of these neoplasms.