Background: Healthcare-associated pneumonia (HCAP) was proposed as a new category of pneumonia in the 2005 ATS/IDSA guidelines, emphasizing that patients with HCAP should be treated with broad-spectrum antibiotics directed at multidrug-resistant (MDR) pathogens. However, this concept continues to be a subject of controversy and there have been no studies about this issue in HCAP patients requiring intensive care unit (ICU) admission. Methods: A retrospective analysis of patients with HCAP who required ICU admission was conducted in a 16-bed medical ICU from March 2011 to June 2012. Clinical characteristics, microbiological distributions, treatment outcomes and prognosis of HCAP were compared to those with community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP). Results: A total of 140 patients (51 with CAP, 53 with HCAP, and 36 with HAP) were included for analysis. Median age of total patients (male, 78%) was 73.5 (19-92), mean APACHE II score was 25.1±9.4 and 134 (95.7%) were applied mechanical ventilator. The incidence of MDR pathogens (CAP, 16.0%; HCAP, 27.6%; HAP, 76.2%; P＜0.001) was significantly different among three groups, especially between HAP and the others. Gram positive pathogens were less frequently cultured in HCAP patients (CAP, 68.0%; HCAP, 27.6%; HAP, 57.1%; P=0.009). There were no significant differences among three groups regarding appropriateness of initial antibiotics treatment, clinical outcomes and prognoses. Conclusions: HCAP in patients requiring ICU admission was more close to CAP, not HAP in terms of the frequency of MDR pathogens.