Enterocytozoon bieneusi is an agent of intestinal microsporidiosis leading to malabsorption syndrome and diarrhea in AIDS patients. Respiratory tract microsporidiosis due to Encephalitozoon spp. has been reported. To date, however, only two cases of pulmonary involvement of E. bieneusi have been documented for patients with intestinal microsporidiosis. We report here another pulmonary localization of E. bieneusi in a human immunodeficiency virus-infected patient. Clinical features of these three cases are reviewed. E. bieneusi can colonize the respiratory tract but could be considered a simple carriage associated with an intestinal infection.