To evaluate the safety and efficacy of gatifloxacin in adults <65, 65 to 79, or > or =80 years old with community-acquired pneumonia, adult male and female outpatients from general community-based practices were enrolled in an open-label, multicenter, noncomparative study. Gatifloxacin 400 mg once daily was administered for seven to 14 days. Medical history, physical examination, signs and symptoms of infection, Gram stain and culture if specimen available, clinical response, and safety were determined. Of 1655 treated patients, 1103 were at least 65 years old, 405 were 65 to 79, and 147 were at least 80. Patients > or =80 years old presented with chills, chest pain, fever, or headache less often than younger patients. Cure rates were 95.5% for patients <65 years old, 96.2% for those 65 to 79, and 90.2% for those at least 80 years old. Neither the frequency nor susceptibility of isolated pathogens appeared to differ with age. Between 93.7% and 100% of subsets of the two younger groups with verified Streptococcus pneumoniae or Hemophilus influenzae were cured. All oldest-group patients in the subset with verified S. pneumoniae and 71.4% (7) of patients with H. influenzae were cured. Each age group, including current or past smokers and patients receiving medications for concomitant conditions, tolerated treatment well. Gatifloxacin is safe and efficacious in adults of any age with community-acquired pneumonia, including the elderly up to 100 years old and patients with S. pneumoniae including penicillin-resistant strains.