Acute myeloid leukaemia (AML) often presents with non-specific symptoms such as fatigue, anaemia or infection. Pulmonary involvement is uncommon in AML during the course of the disease and is usually caused by infection, haemorrhage, leukaemic pulmonary infiltrates and leukostasis. Lung localization of AML is very uncommon and potentially life threatening if not diagnosed and treated rapidly. The authors describe the sudden death of an asymptomatic five-month-infant because of a misdiagnosed lung localization of AML. Autopsy examination followed by histopathological studies showed an extensive leukostasis and extramedullary leukaemic infiltrating the lungs. Special stains and immunohistochemical studies revealed findings consistent with acute myelogenous leukaemia. This case suggests that underlying acute leukaemia should be considered as a cause of flu-like symptoms in infants. Medical personnel are urged to be alert to fever, sore throat, weakness and dyspnea that may be characteristic of serious systemic diseases.