OBJECTIVES: Pneumoniae are typical infections of the lower respiratory tract. The objective of this analysis was to assess the economic impact of pneumoniae requiring hospitalizations. METHODS: Using DENALI datawarehouse, linking administrative healthcare claims of Region Lombardy inhabitants, we detected all subjects who were hospitalized for pneumonia (primary diagnosis ICD-9 CM: 480-486) during the period January 2006 – December 2008. The hospital admission date was used as index date. Demographic and comorbidity (Charlson Comorbidity Index, CCI) data were evaluated. The study estimated costs of the episode requiring hospitalization, and costs during the 30 days preceding and following the index date. Matched comparison was performed between 30-day per-patient costs in the post and pre-index period. RESULTS: During the study period, 18,516 subjects (59% male, mean age 70.8 years) experienced at least one hospital admission for pneumonia (around 6,000 per year). Most patients (68.4%) had a CCI >1 with chronic obstructive diseases and cardio-cerebrovascular diseases being the most common comorbidities. Overall costs for hospitalizations amounted to about €68mln in three years (€3,176 per-hospitalization). The mean (median) length-of-stay was 13 days (10 days): it significantly increased with the increasing of CCI. Twenty-seven percent of patients died within 1-year following hospitalization. During the first 30-day post-index period, patients had significant (p<0.01) higher costs than during the 30-day pre-index period (€36 versus €25 per-day, respectively, excluding the cost of the index hospitalization). Costs over the 30-day post-index period were mainly attributable to further hospitalizations (81.4%), followed by pharmacological therapy (12.7%) and ambulatory care (5.9%). Drugs for respiratory system and anti-infectives for systemic use were the most prescribed therapies in this period. CONCLUSIONS: The economic burden of pneumoniae is high, mainly due to the high costs of hospitalizations and relative length-of-stay. The comparison between the 30-day pre/post period showed the extent by which the acute episode triggers further healthcare interventions.