Neonatal leukaemia is defined as occurring within the first 28 days of life and most, if not all, cases are congenital. With the exception of Down syndrome‐associated transient abnormal myelopoiesis, which is not considered here, neonatal leukaemias are rare. In two‐thirds of patients the disease manifests as an acute myeloid leukaemia, frequently with monocytic/monoblastic characteristics. Most other cases are acute lymphoblastic leukaemia, particularly B lineage, but some are mixed phenotyp...