All episodes of bloodstream infection in patients admitted to a Norwegian university hospital in 1974–1979 and in 1988–1989 were analyzed; altogether, there were 1,447 episodes involving 1,286 patients, and 54.3% of all episodes were hospital-acquired. The incidence of bloodstream infection increased between the two periods studied from 4.26/1,000 admissions to 8.71/1,000. Crude mortality rates were 27.6% and 18.8% and attributable mortality rates were 12.3% and 6.9% in the first and second periods, respectively. Patients >60 years of age accounted for more than half of the bloodstream infections; mortality in this group was significantly higher than that among younger patients (31.4% vs. 13.9%). The frequency of isolation of Enterobacteriaceae decreased from 48% in the first period to 34% in the second, while the rate of isolation of coagulase-negative staphylococci increased from 6.5% to 16.9%. The shift in etiology may be explained in part by the occurrence of significantly more bloodstream infections related to intravascular devices, endocarditis, and skin and wound infections and of significantly fewer episodes related to abdominal or genitourinary disease in the second than in the first period. Almost all isolates of Enterobacteriaceae were susceptible to newer cephalosporins and aminoglycosides. In 1974–1979, 96 (69.1%) of 139 patients with septic shock died; in 1988–1989, the figure was 35 (52.2%) of 67 patients (P = .019). Clinical factors predictive of an adverse outcome were septic shock (odds ratio for first/second period, 12.7/4.6), intensive care treatment (not significant/10.6), malignant disease (4.6/2.6), any underlying disease (4.2/not significant), diabetes mellitus (3.6/not significant), age of >60 years (not significant/3.0), and pulmonary source of infection (not significant/2.8).