Branhamella catarrhalis is increasingly reported as a cause of pneumonia in the immunocompromised host. The authors here report what they believe to be a unique case of B catarrhalis bronchopneumonia in a patient who had previously acquired miliary tuberculosis. The patient initially responded to medication but died suddenly following a brief episode of febrile illness. At autopsy, several lines of evidence implicated B catarrhalis in the findings. The authors review the literature regarding cases of lower respiratory tract infection reportedly caused by B catarrhalis. Their own conclusion is that B catarrhalis infection is not necessarily caused by abnormal immunoglobulin, as some workers have suggested, but rather by damaged lung tissue in general and damaged bronchoalveolar cells in particular.