One gram once daily of ceftriaxone is as effective as 2 gm for the common causative organisms of community-acquired and nosocomial pneumonias. It should not be used alone against L. pneumophila, the TWAR pneumoniae, and possibly anaerobic pathogens. Preliminary study suggests that a regimen of 500 mg a day may be effective in selected patients with simple pneumonias caused by sensitive pathogens. Ceftriaxone is safe, well tolerated, and cost-effective, which means it can play a significant therapeutic role in nursing homes and other long-term care facilities as well as in outpatient therapy.