Comparison of 35 elderly patients hospitalized with pneumonia acquired in nursing homes and 35 elderly patients hospitalized with community-acquired pneumonia showed that 16 (47.1%) of the nursing home patients had received previous antibiotic therapy compared with two (5.9%) of the community patients. Klebsiella pneumoniae was isolated in 14 (40%) of the nursing home patients, but in only three (8.6%) of the community patients. Staphylococcus aureus was also more frequent in nursing home patients (nine, 25.7%) compared with community patients (five, 14.3%). Persons hospitalized with nursing home-acquired pneumonia should be treated initially with antimicrobial agents active against K pneumoniae and S aureus unless the clinical picture strongly suggests otherwise.