We did a prospective study of the clinical, laboratory, radiologic, and therapeutic features of acute, symptomatic, bacterial pyelonephritis in 35 consecutive elderly, noncatheterized patients who required hospitalization. Pyelonephritis had been identified as the most common cause of gram-negative bacteremia in elderly patients admitted to a community hospital. Appropriate antibiotic therapy and, of equal importance, a lack of serious associated medical illnesses contributed to the 97% survival. Two features appear to distinguish acute, symptomatic, bacterial pyelonephritis in elderly women from that in young women: an increased incidence of bacteremia and septic shock. We provide guidelines for the diagnostic evaluation and antibiotic therapy of acute, symptomatic, community-acquired, bacterial pyelonephritis in the elderly.