Background: Ventilator-associated pneumonia (VAP) is one of the most common hospital-acquired infections in the intensive care units (ICUs). They have not only an impact on each patient’s individual health but also result in a considerable financial burden for the healthcare system. Our aim was to estimate the cost and mortality rate of VAP on the level III ICUs of the Central Lisbon Hospital Center (CHLC). Methods: We used a retrospectively cohort design, comparing patients with VAP and without VAP. VAP was defined by international classification of diseases, ninth revision, clinical modification (ICD-9-CM), code 997.31. All patients hospitalized in the 2016 for more than zero days and discharged up to 31 December 2016 with 18 or more years old were included in the CHLC’s four level III ICUs. The identification of episodes and mortality rate was calculated using hospital morbidity database of the Central Administration of the Health System, I.P of 2016. The costs of all episodes were calculated using the CHLC’s analytical accounts of same year. Results: Of 599 eligible patients, 15 (2.5%) had VAP. The patients with VAP experienced significantly longer hospital stay (39 days versus 18 days, p = 0.001), as well as longer ICU stay (16 days versus 6 days, p < 0.001). The attributable hospital costs for ICU-acquired VAP was significantly higher compared to the patients without infection (30.918,16€ versus 10.575,74€, p < 0,001). There was no statistically significant difference in mortality among the groups (p = 0.623). Conclusions: VAP is one of the most common hospital-acquired infections in ICUs. ICU-acquired VAP is associated with increased hospital costs and prolonged hospital stay. Hospital management should therefore implement control measurements to keep the incidence of ICU-acquired VAP as low as possible.