The treatment of bacterial pneumonia requires an agent with activity against a wide range of bacterial pathogens, including pathogens that produce beta-lactamase. Loracarbef, a member of the carbacephem class of antibiotics, was tested in a series of clinical trials for its efficacy and safety in the treatment of lobar and bronchial bacterial pneumonia. Successful clinical responses were achieved in 97.6% of the evaluable patients receiving 400 mg twice daily of loracarbef. This compared favorably with the respective response rates of 92.3% for patients receiving 500 mg three times a day of amoxicillin/clavulanate and 95.0% for patients receiving 500 mg three times a day of amoxicillin for the same illnesses. Proven or presumed elimination of the pretherapy pathogen was found in 89% of the patients receiving loracarbef, 92.3% of the amoxicillin/clavulanate-treated patients, and 70.0% of those receiving amoxicillin. Loracarbef was also well tolerated, although nausea and vomiting were associated with the use of all three agents. Nevertheless, treatment with loracarbef resulted in the lowest rate of discontinuation of therapy due to drug-related adverse events. Thus, these clinical trials support the conclusion that loracarbef is a safe and effective treatment for bacterial pneumonia.