The increasing frequency of Gram-negative bacteremia, its ecology, and the importance of host factors in its outcome were emphasized in a preceding paper which reviewed the occurrence of these infections during an 8-year period at the University of Illinois Hospitals.1The severe, often rapidly fatal nature of Gram-negative bacteremia, especially in patients with important underlying diseases, makes prompt recognition highly desirable for the early institution of optimal therapy. Certain features of the syndrome permit its clinical recognition and differentiation from other hospital-acquired infections. Most authors have emphasized the occurrence, therapy, or individual factors other than diagnostic clinical features. The present report describes the clinical manifestations, biochemical alterations, and treatment of 173 patients with Gram-negative bacteremia. Evaluation of the use of antibiotics, corticosteroids, and vasopressors included consideration of the nature and severity of the patient's underlying illness which we have shown to exert a profound effect on the outcome of