The incidence of Pseudomonas aeruginosa bacteremia was examined in 5,882 burn patients consecutively admitted over a 25-year period to one burn center. The population examined had an average burn size of 33.8% of the body surface and an average age of 26.3 years. Pseudomonas aeruginosa bacteremia occurred in 540 patients. These patients had an average burn size of 54.2% and average age of 28 years. Mortality was 77%. Bacteremia with other organisms occurred during hospitalization of all but 128 of the 540 patients. Comparison of predicted mortality based on burn size and age to observed mortality showed Pseudomonas aeruginosa bacteremia to be associated with a 28% increase in mortality. Examination of mortality as a function of time showed no significant change over the 25-year period. The incidence of Pseudomonas aeruginosa colonization and infection was examined in 400 recently admitted burn patients. Colonization occurred in 107 and 34 infections were recorded in 27 of the colonized patients.