Community-acquired pneumonia (CAP) is an infectious disease with high morbidity and mortality and a major social and economic impact. A budget impact model was developed to estimate the impact on hospital direct costs of different antibiotic therapies suggested by international and national (FADOI) guidelines on treatment of patients hospitalized with CAP. The model includes the costs of drugs, staffing, consumables and in-patient stays in two different scenarios: intravenous therapy only and switch therapy; it compares levofloxacin (monotherapy) versus other combination therapies as suggested by the guidelines and includes the cost of failure of first-line treatment. Budget impact analysis shows that the cost of CAP-hospitalized patients in Italy consists mainly in the cost of treatment failure while that of antibiotics is just a small component of total direct costs incurred by hospitals.