Summary A 48-year-old woman presented with suspected acute myelogenous leukaemia with a leucocyte count of 80×109/L. On admission, she had high fever and shortness of breath. Chest X-ray demonstrated unilateral consolidations of right lung suggestive for pneumonia and broad spectrum antibiotics were started. Her condition rapidly deteriorated and despite the clinical diagnosis of pulmonary leucostasis and treatment with leucapheresis the patient died within 2 days after admission from progressive respiratory failure and multiorgan failure. Autopsy showed diffuse leucostasis in the pulmonary capillaries. The present case illustrates that pulmonary leucostasis may be presented by unilateral chest X-ray abnormalities and without clear neurological symptoms (headache and blurred vision). Clinicians should be aware of this since delayed treatment may increase mortality.