Acute leukaemia is characterised by uncontrolled expansion of immature leukocytes, either myeloid or lymphoid progenitors, leading to acute myeloid leukaemia (AML) and acute lymphoid leukaemia (ALL), respectively. If left untreated, it is life-threatening and can lead to death within weeks. When acute leukaemia is suspected, urgent haematology input should be sought. Appropriate investigations are needed promptly to confirm diagnosis and start treatment. A multidisciplinary approach is vital to ensure appropriate management.