OBJECTIVES: The private health care system in Brazil currently assists 47,008,888 individuals in Brazil. This study has the objective of evaluating the cost-effectiveness of azithromycin 500mg/day QD and clarithromycin 1g/day BID for the treatment of CAP for immunocompetent individuals age 65 and older from the private healthcare perspective in Brazil. METHODS: A decision-tree model, built based on the following health states: death, cure and discontinuing due to adverse events (phlebitis, diarrhea, infusion reaction which would lead to switching the antibiotics). Risks and length of treatment were obtained from the literature and prices were retrieved from the Brazilian Hierarchic Classification of Medical Procedures (CBHPM 4th edition - 2005) and public databases. Resource Utilization (exams, procedures and materials) were gathered based on the latest clinical guidelines for CAP defined by the Brazilian Society of Pneumology. The time horizon was defined as one year. Effectiveness was expressed as life years gained (LYG). Values were expressed in 2011 USD. First order probabilistic sensitivity analysis was carried by Monte Carlo simulation of 10,000 iterations considering the range of values for the lengths of treatment in a normal distribution. RESULTS: The simulation considering 10,000 iterations showed the following values for azithromycin and clarithromycin respectively: Total LYG [9,640 vs. 8,840]; average costs per treatment [USD863.76 vs. USD1,384.15]; average cost-effectiveness ratio [USD896.04/LYG vs. USD1,566.18/LYG], representing a cost saving of USD 670.14/LYG for azithromycin. Considering 100,000 cases of pneumonia hospitalizations for adults age 65+, the total savings for the incorporation of azithromycin would be approximately USD 52.072.571. CONCLUSIONS: In this analysis, azithromycin presented the greatest effectiveness diminishing costs, by reducing mortality and treatment discontinuation due to adverse events, from the Brazilian private health care system’s perspective.