Objective To explore the diagnostic value of gram-stained sputum smears in elderly patients with ventilator-associated lower respiratory infection (VALRI).Methods 368 elderly patients undergoing mechanical ventilation over 48 hours in ICU were retrospectiely analyzed from Jun 2009 to Jun 2011.42 patients fulfilled the inclusion criteria (with good-quality sputa and presence of the same microorganism in sputum and blood cultures).58 gram-stained smears and sputum cultures were obtained and analyzed.Results The diagnostic sensitivity and specificity of Gram-positive bacteria and Gram-negative bacteria by gram-stained smears were 82.35％ and 78.05％,80.49％ and 82.35％,respectively.The positive and negative predictive value of Gram-positive bacteria and Gramnegative bacteria were 63.64％ and 91.43％,91.67％ and 60.87％,respectively.The coincidence rates in diagnosing Gram-positive bacteria and Gram-negative bacteria were 81.03％ and 79.31％,respectively.Conclusions Gram-stained sputum smear is reliable in diagnosing ventilator-associated lower respiratory infection in elderly patients,and has a certain clinical significance in guiding to the selection of antibiotics.