SummaryThe authors have looked for fever and infections in a hundred consecutive cases treated in a medical intensive care unit. These patients suffered from severe intoxication, respiratory insufficiency, myocardial infarction, neurological diseases or endocrine disorders. Sixty-seven patients had fever, due to infection in at least 41 cases, 35 of which had a respiratory infection. Most of the patients with non-infectious fever had a myocardial necrosis or a cerebral affection. Twenty-seven patients acquired an infection within the unit ; these hospital-acquired infections are mainly due to fungi and to Gram-negative organisms. Many factors contribute to contaminate the patients : venous and urinary catheters, artificial ventilation, coma, spontaneous hypothermia, antibiotics, corticoids, etc. The main principles of the prevention of infections in intensive therapy units are recalled.