Acinetobacter baumannii is a significant cause of nosocomial pneumonia, especially late ventilator-associated pneumonia. In Spain, A. baumannii is the third leading pathogen after Pseudomonas aeruginosa and Staphylococcus aureus. Risk factors for pneumonia due to A. baumannii are head injury, neurosurgery, acute respiratory distress syndrome, aspiration, and previous antibiotic therapy. Definitive diagnosis requires respiratory samples and invasive techniques with quantitative cultures to differentiate true infections from simple colonizations. The crude mortality of patients with ventilator-associated A. baumannii pneumonia is high, although the attributable mortality is controversial. Adequate empirical antimicrobial therapy of A. baumannii pneumonia is a protective factor, even though the therapeutic options are often limited. The treatment of choice is imipenem and sulbactam may be considered an acceptable alternative. Nowadays, colistin is the treatment of choice in A. baumannii pneumonia caused by panresistant strains. The associations of imipenem and rifampin or imipenem and sulbactam may be acceptable alternatives to colistin in infections caused by these strains. Surveillance measures are essential to eradicate this multidrug-resistant pathogen in outbreaks and reduce the number of episodes in endemic situations. Although these measures are important throughout the hospital, intensive care units are especially high-risk areas.