ObjectiveTo evaluate the significance of sputum smear gram staining in the early diagnosis and guidance for antimicrobial treatment of hospitalacquired pneumonia (HAP) in intensive care unit patients.MethodsFrom March 2011 to February 2012, sputum samples taken from lower respiratory tract of 289 patients with  suspected HAP were performed gram staining and culture, the isolated pathogens were identified, results of two methods were compared.ResultsA total of 890 sputum specimens were sent for detection , 790(88.76%)  specimens were qualified. A total of 520(65.82%) pathogenic strains were isolated , 330 isolates were gramnegative bacteria, 130 were grampositive bacteria, and 60 were fungi. The concordance between the results of two methods was 72.15%（570/790）, there was no significant difference between two methods(χ2=1.818,P=0.2000). The sensitivity and specificity of sputum smear gram staining was 80.77% （420/520）and 55.56% （150/270）respectively, the positive predictive value and negative predictive value was 77.78% （420/540）and 60.00% （150/250）respectively.ConclusionGram staining of the qualified sputum samples of lower respiratory tract is helpful in early diagnosis and treatment of HAP.