OBJECTIVES:  Community acquired pneumonia (CAP) still represents an important disease in Mexico. The study of both economic and clinical outcomes of treatments remains relevant. The aim of this study was to assess the consequences of the use of antibiotics to treat CAP, from the perspective of Instituto Mexicano del Seguro Social (IMSS). METHODS: A decision tree model that considers clinical success and failure either whit first and second line treatments, presentation or not of adverse events (AE´s), as well as death was developed. The antibiotics considered in the assessment were: clarithromycin (1,000 mg/day), levofloxacin (1,000 mg/day), ceftriaxone (1,000 mg/day), cefuroxime (1,500 mg/day), moxifloxacin (400 mg/day) and gemifloxacin (320 mg/day). The last option is not listed in IMSS formulary. Clinical data were extracted from international literature. Effectiveness measures were clinical success rate and length of stay (LOS). The model considered direct medical costs (2012 US$): drugs, diagnostic tests, physician visits, LOS, emergency room and intensive care unit; cost were extracted from institutional sources.  Resource use for CAP was extracted from clinical files (n=94 adult patients) treated at one IMSS hospital, whereas resource use for AE´s treatment was obtained through expert opinion (panel). One-way sensitivity analysis and acceptability curves were performed. RESULTS: The alternative that presented the most favorable pharmacoeconomic profile was gemifloxacin ($3237 per patient, 95.3% of success rate and 6.22 days of LOS), followed by levofloxacin and clarithromycin, with marginal differences in  clinical success but around $1600 of incremental cost. The alternative with the less favorable profile was moxifloxacin: $1784.52 of incremental cost, -8.8% of clinical success and +6.6 days of LOS regarding gemifloxacin. The results were robust to +10% acquisition cost and +5% AE´s incidence for gemifloxacin. CONCLUSIONS: Alternatives with potential to promote savings in the management of CAP (like gemifloxacin) are valuable, which becomes more relevant in contexts with limited resources.