BACKGROUND: With beta-lactam drugs and immunosuppressants widely used, the infection caused byAcinetobacter baumannii (Ab) has become more and more serious with multidrug resistant Acinetobacter baumannii (MDRAb) emerging and worsening rapidly. Compared with other patients, the incidence and multidrug resistance of MDRAb are higher in children in pediatric intensive care unit (PICU) because of immune deficiency, severe basic diseases, prolonged hospitalization and invasive operations. Hence it is significant to study the epidemiology and changes of antibacterial susceptibility in order to reduce the incidence of MDRAb in children. METHODS: A total 115 patients with MDRAb pneumonia and 45 patients with negative MDRAb (NMDRAb) pneumonia who had been treated from January 2009 to August 2011 were studied retrospectively at the PICU of Wuhan Children's Hospital. Clinical data were analyzed with univariate and multivariate Logistic regression. RESULTS: In 176 clinical strains ofAcinetobacter baumannii isolated, there were 128 strains of MDRAb, accounting for 72.73％. Drug susceptibility tests showed that the resistance rates of β-lactam antibiotics were more than 70％ except for cefoperazone sulbactam. The rates to carbapenems were higher than 90％. They were significantly higher than those of NMDRAb. Amikacin, levofloxacin, ciprofloxacin and minocycline had the lowest drug-resistance rates (<20％). Multivariate Logistic regression revealed that ICU stay, the time of mechanical ventilation, anemia, hypoproteinemia and the use of carbapenems were independent risk factors for MDRAb pneumonia. CONCLUSIONS: MDRAb is an important opportunistic pathogen to pneumonia in PICU, and its drug-resistance is severe. It increases significantly the mortality of patients. It is important to take the effective prevention measures for controlling it.