The study will assess the clinical efficacy at Day 14-21 (Test of Cure), 14-21 days after starting the study drug; those subjects from whom a baseline pathogen is identified will also be assessed for bacteriologic response. All subjects who receive 1 dose of study medication will be assessed for safety.

Inclusion Criteria:

• Male or female, 18 years age or older, for whom oral, outpatient therapy is indicated.
• Diagnosis of CAP as manifested by at least 3 or more of the following:
• cough, pleuritic chest pain, fever (temperature of >37.8 C to <40 C), auscultatory findings on pulmonary examination of rales and/or evidence of pulmonary consolidation, dyspnea, tachypnea, laboratory results of elevated total peripheral white blood count (WBC> 10,000/mm3 or greater than 15% immature neutrophils (bands)

Exclusion Criteria:

• Known or suspected hypersensitivity or intolerance to azithromycin or other macrolides.
• Previously diagnosed disease(s) of immune function, including: subjects with baseline absolute neutrophil count < 1,000/mm3, HIV positive subjects with CD4 count < 200 cells/mm3, any immunoglobin or neutrophil disorder.