A 38 year-old woman, who was previously fit and well, presented with a 10 day history of fever and non-specific symptoms. Initial chest X-ray demonstrated patchy nodular infiltrates bilaterally. She became increasingly hypoxaemic. Cultures to this point were all negative. A high-resolution CT thorax showed diffuse multilobular ground glass appearance with peripheral nodular shadowing, consistent with a viral pneumonia. CMV IgM antibody was positive and CMV PCR was positive on two subsequent occasions. She was commenced on oral valganciclovir. She made a full recovery and was discharged seven days later.