Ofloxacin therapy in common infections of the elderly was studied prospectively in acute and chronic care facilities. Forty-six acute care subjects over 55 years of age were randomized to receive ofloxacin, administered either intravenously or orally, and compared with standard therapy with ceftriaxone or ceftazidime. Parenteral therapy was changed to oral therapy when clinically appropriate. Long-term care subjects were enrolled into an open study of oral ofloxacin. The mean age of subjects was over 80 years. For the acute care facility arm, the clinical and bacteriologic outcomes were similar in both ofloxacin and standard therapy groups. For the open study in long-term care patients, 93% were cured or improved. Assessments of mental and functional status were largely unsuccessful for subjects enrolled into the comparative arm because of initial severity of illness. For the noncomparative arm, antimicrobial therapy was associated with a significant improvement in mental status measurements. Ofloxacin is effective therapy for the treatment of pneumonia, skin and skin structure infection, and urinary tract infection in elderly subjects. The option of oral therapy may provide a benefit when compared with other regimens in this population.