|Patients with VAP in ICU have a high mortality rate. The routine surveillance cultures obtained previously or ATS guidelines for hospital-acquired pneumonia are used in selecting initial antimicrobials. The object of this study is to compared the respiratory samples before VAP and BAL culture. Material and Methods: Fifty-four patients underwent fiberoptic bronchoscopy to obtain washing and BAL samples. We reviewed microbiologic specimen results of prior respiratory speciemens (pre-VAP) and BAL. Results: Among 54 patients, 58 microorganisms of pre-VAP and 56 samples were isolated. Pre-VAP includes 20.7% of MRSA. 20.6% of multidrug resistant-Acinetobacter baumannii (MDR-AB) and 10.3% of Stenotrophomonas maltophilia. BAL samples were 25.0% of MRSA, 32.1% of MDR-AB, 14.3% of Stenotrophomoas maltophilia and 3.6% of Klebsiella pneumonia in order. Pre-VAP samples compared to BAL samples, only 33.3% were identical. BAL samples compared to bronchial washing samples obtained on the same day of onset of VAP, 61.9% were identical (p=0.059). BAL samples compared to pre-VAP samples obtained in 5 days before the onset of VAP, only 41% were identical. However, BAL samples compared to pre-VAP samples obtained greater than 5 days, 13.3% were identical (p=0.047). Conclusion: Based on these data, pre-VAP samples obtained before 5 days of onset of VAP may help to predict the causative microorganisms and to select an appropriate initial antimicrobials.