Aspiration of oral secretions and their bacteria, especially gram-negative bacilli, is increasingly being recognized as an important factor in pneumonia. We investigated whether oral care reduces the frequency of pneumonia in the institutionalized elderly. Nurses or caregivers cleaned patients' teeth with toothbrushes after each meal, and scrubbed the oropharynx with an applicator with povidone iodine (1%) every day. Dentists or dental hygienists gave professional care once a week. During follow up, pneumonia decreased significantly in patients with oral care. Oral care was of benefit for both edentate as well as dentate subjects, although periodontal diseases might cause pneumonia. We suggest that oral care may be useful in preventing pneumonia in institutionalized elderly, irrespective of dentate or edentate status.