A total of 980 episodes of clinically and bacteriologically proven septicemia were included in four prospective 1-year studies at a 1,300-bed university hospital in Berlin between 1979 and 1989. The incidence was 8.1 per 1,000 admissions. The percentage of patients with severe underlying diseases increased significantly from 67% to 95% over the decade. Septicemia due to gram-positive bacteria decreased from 47.3% in 1979 to 43.7% in 1986 and increased again to 51.2% in 1989. Septicemia due to gram-negative organisms decreased constantly from 45.0% in 1979 to 39.8% in 1989. The most frequently isolated species were Escherichia coli (26.4%), Staphylococcus aureus (18.9%), coagulase-negative staphylococci (10.2%), enterococci (7.7%), viridans streptococci (6.4%), Klebsiella species (5.5%), and pneumococci (5.0%). The overall mortality rate decreased significantly from 33.6% in 1979 to 20.8% in 1989. Mortality for episodes of septicemia due to gram-positive bacteria (25.5%) was higher than that for septicemia due to gram-negative bacteria (18.3%). Mortality rates associated with polymicrobic and fungal septicemia were higher than the overall mortality rate.