SummaryThe authors present a series of 100 cases of Gram negative septicemia, in which etiology, clinical features, septic shock (35 cases), bacteriology, laboratory findings, treatment, course (47 deaths) and post-mortem examinations (30 autopsies) have been studied.They discuss the hospital-acquired infections, the prognostic value of underlying diseases, the antimicrobial therapy and the treatment of endotoxic shock.They insist on appropriate management of the initial focus of infection, on gentamicin-ampicillin and gentamicin-cephalotin associations and, in septic shock, on plasma volume expansion.