OBJECTIVES: To compare length of stay (LOS) and costs in hospitalized Community Acquired Pneumonia (CAP) patients treated with levofloxacin ( levo ), moxifloxacin (moxi ) or azithromycin plus ceftriaxone combination therapy ( combo ). METHODS: A retrospective observational study was conducted using medical chart and administrative claims data. Adult CAP patients hospitalized during January 1, 2003-December 31, 2005 were identified based on medical claims. Hospital charts were extracted and those who received levo, moxi or combo therapy were evaluated. Primary outcomes were LOS and hospitalization cost. Patient demographic and clinical characteristics (including the pneumonia severity index PSI) were collected. Generalized linear regression compared the outcomes among the treatment groups. RESULTS: A total of 269 (levo 110; moxi 118; combo 41) patients who received study medications in hospital were included in analysis. Demographics and baseline characteristics between the groups were comparable (mean age 53.3 years; 49% male, 38% PSI Risk class IV-V). Mean adjusted LOS was 3.6 days among levo-treated patients, and 4.3 and 5.0 days in patients treated with moxi and combo therapy, respectively. After adjusting for patient characteristics, combo therapy-treated patients had significantly longer mean LOS than levo-treated patients (P=0.038) but the difference in LOS between levo- and moxi-treated patients did not reach statistical significance (P=0.106). Mean adjusted hospital costs were $7,187, $7,941 and $8,625 in levo-, moxi- and combo therapy-treated patients, respectively and did not differ significantly between groups. CONCLUSIONS: Hospitalized CAP patients treated with levo had significantly shorter mean LOS compared with patients receiving combo therapy. Trend toward lower hospital costs was observed in levo group compared with either moxi or combo therapy.