Mycoplasma pneumoniae infections occur frequently throughout the population but rarely result in hospital admission. We recently identified two young adults, who presented at the emergency department with fatigue, jaundice and fever. Both patients were diagnosed with acute severe Coombs-positive autoimmune haemolytic anaemia (AIHA) based on cold-agglutinins. Serological examination revealed a recent infection with Mycoplasma pneumoniae in both cases. Case number 2, a 40-year-old male, was even admitted to our Intensive Care Unit (ICU) with respiratory failure caused by bilobular interstitial pneumonia and severe haemolysis. Fortunately, he responded well to treatment and was discharged after one week. Although M. pneumoniae infection rarely results in hospital admission, the combination of bilobular interstitial pneumonia with severe haemolysis may even lead to admission to an ICU. Therefore, physicians should be aware of the potential harm that M. pneumoniae can cause, especially in combination with life-threatening haemolysis. Copyright © 2008, Nederlandse Vereniging voor Intensive Care. All Rights Reserved.