['Haemophilus species are a common cause of community-acquired pneumonia; however, their significance in posttraumatic pneumonia is unclear.', 'Case series.', 'University hospital, level I trauma center.', 'Two hundred fifty-seven consecutive patients with blunt and penetrating trauma treated for pneumonia.', 'Length of stay in the intensive care unit, duration of ventilatory support, rate of recurrent or persistent pneumonia, and mortality.', 'Ninety-six (37%) of 257 patients treated for pneumonia had a Haemophilus species isolated on sputum culture. Of these 96 patients, 49 (51%) had only Haemophilus species, while 33 (34%) had associated gram-positive organisms and 14 (15%) had gram-negative organisms. Seventeen pure cultures (29%) and seven mixed cultures (15%) (P < .05) were beta-lactamase-positive trains. Compared with patients who had pneumonia caused by other bacteria, patients with Haemophilus species were younger (mean +/- SE, 35 +/- 1.7 vs 42 +/- 1.6 years; P < .05) and more severely injured (Injury Severity Score, 20.7 +/- 1.1 vs 17.5 +/- 0.9; P < .05). There were no differences in any outcome variables between the two groups. Only one (1%) of 96 patients had persistent Haemophilus species on sputum cultures after 7 days of treatment.'] Is haemophilus pneumonia a common cause of early pulmonary dysfunction following trauma?