SummaryFrom October 4 to November 4, 1957, 16 patients were admitted into our department for pulmonary complications of influenza. Five of these individuals died. The group who recovered included 6 males and 6 females, from 16 to 62 year old.In 4 of those who recovered, the pulmonary complication started at the beginning of the disease. There was an interval of 3 to 7 days in seven. Seven cases were suffering from some predisposing condition such as asthma, mitral stenosis, chronic bronchitis, furunculosis or pregnancy.The series includes 10 cases of pneumonia or bronchopneumonia and 1 case of pulmonary abscess. Four cases of bronchopneumonia were respectively complicated by septicemia, pyothorax, pyopneumothorax or localized peritonitis. Specific antibodies were demonstrated in the serum in every case, but the virus could not be isolated from pharyngeal secretions in any case. Sputum cultures showed various pathogens which were sensitive to all common antibiotics, and in some treated cases, Coli Bacillus and Monilia. In the 4 cases with complications and in the one with pulmonary abscess, Staphylococcus Aureus was abundant, and sensitive to all antibiotics, except to penicillin.In the cases who died (5 females 16 to 51 year old) the complications followed the influenza without free interval. Two of these patients had no known previous disease. In three there were previous histories of epilepsy and diabetes, asthma and pregnancy, operated mitral stenosis and pregnancy. Four cases showed bilateral broncho-pneumonia on admission and one lobar pneumonia. Influenza virus was found in four cases and not looked for in one. In the five cases, lung culture obtained by lung aspiration showed Staphylococcus Aureus, sensitive to all antibodies, except generally to penicillin and streptomycin. Death supervened from 2 to 44 hours after admission, from asphyxia and shock, despite the administration of high dosages of antibiotics, oxygen, norepinephrine and hydrocortisone.The pathological findings included :a) Haemorrhagic pneumonia with suppurative bronchopneumonia;b) Epithelial necrobiosis followed by extensive desquamation of the bronchial mucosa.