A 56 year old man with previously unsuspected recurrence of squamous cell carcinoma of the oesophagus presented with dyspnoea. Bronchoscopy and computed tomography suggested bronchopneumonic changes with an infectious cause. He suffered a rapidly deteriorating course and died despite active treatment, including antibiotics and mechanical ventilation. Necropsy revealed a florid pulmonary tumour microembolism mimicking alveolitis. No bronchopneumonia was seen. The emboli arose from loosely attached tumour vegetations in the tricuspid valve. In a patient with known malignancy, tumour microembolism should be considered as an uncommon cause of rapid respiratory failure, refractory to antibiotic treatment.