A 47-year-old woman was admitted to hospital with severe Legionella pneumonia. The respiratory symptoms improved dramatically and the X-rays revealed a decrease in the diffuse chest infiltrates after treatment with erythromycin and rifampicin. However, chest CT scans showed that the reticulonodular opacities persisted for several weeks after the onset of pneumonia. Two months after admission, the chest X-rays showed the progression of small nodules in both lungs and there was increasing respiratory distress. A diagnosis of miliary tuberculosis was confirmed. The present case should alert physicians to this potentially confusing combination of respiratory pathogens.