Case report A 49-year-old previously healthy man was admitted to the ICU after cardiac arrest following a short history with headache, blurred speech and reduced consciousness. After cardiopulmonary resuscitation perfusion rhythm was regained, but the patient didn`t regain consciousness. The arterial blood gas analysis at the ICU revealed a severe metabolic acidosis with pH at 6.86 and lactate levels of 16 mmol/L. The white blood cells count was also markedly increased (312 * 109/L), and blood smear showed immature cells indicating acute leukemia. The severe metabolic acidosis, at first thought to be due to systemic hypoperfusion, did not improve in spite of fluid and vasopressor resuscitation. A CT scan of the head performed the next day, revealed massive cerebellar haemorrhage, edema in both hemispheres and signs of anoxic brain damage. Immunophenotyping of peripheral blood was consistent with Acute Myeloid Leukemia (AML).