In order to determine the epidemiology, microbiology, and outcome of bacteraemia originating in the urinary tract in hospitalised patients, a prospective study was conducted in a large general hospital in Israel. Data from all patients with bacteraemia were collected prospectively, and a subgroup of patients with bacteraemia secondary to urinary tract infection was analysed. There were 702 episodes of bacteraemia secondary to urinary tract infection during a five-year period (33.9% of all episodes of bacteraemia). The mean age of the patients was 76 years, and the male:female ratio was 0.9:1.0. The most common pathogens were Escherichia coli (52%), Klebsiella spp. (14%), and Proteus spp. (9%). Pseudomonas spp. were isolated from 8% of all patients, from 19% of those who had received antibiotics, and from 15% of males. Enterococcus spp. were isolated from 4% of males but from no females. Five percent of the episodes were polymicrobial, and 16% of the infections were hospital acquired. On logistic multivariate regression analysis, predictors of mortality were: hospitalisation in a medical department, hospital-acquired infection, inappropriate empiric antibiotic treatment, presence of decubitus ulcer(s), respiratory or renal failure, and elevated urea and decreased albumin levels.