We reviewed 105 patients age 65 or older who were admitted with “urosepsis,” which we defined as urinary tract infection plus at least one of the following: Fever (temperature >38°C), hypothermia (temperature <35.5°C), hypotension (systolic blood pressure <90 mm Hg), or change in mental status. Blood cultures were positive in 50%; bacteremia was predicted only by the presence of hypotension (P <.05), but this sign was not sensitive enough to exclude bacteremia in patients without hypotension. One hundred (95%) were infected with a gram-negative rod; of these, 53 were Escherichia coli, of which 12 (22%) were resistant to ampicillin. Of the 47 non-E. coli gram-negative rods, 26 (56%) were ampicillin resistant. Sixteen of the 100 gram-negative rods were resistant to multiple antibiotics. Stepwise logistic regression analysis showed recent hospital admission and nursing home residence to be independent predictors of infection with multiply resistant gram-negative rods (P <.01). No factors were predictive of infection with ampicillin-resistant gram-negative rods. We conclude that bacteremia and resistance to ampicillin were common and unpredictable in elderly patients admitted with urosepsis but that a subset of patients at risk for multiply resistant gram-negative rods may be identified at the time of admission. © 1993 by Williams & Wilkins.