Objective. Our objective was to compare the results of a blind lavage vs a bronchoscopic-guided bronchoalveolar lavage for the etiologic diagnosis of ventilator-associated pneumonia (VAP).Design. Prospective study in consecutive patients with high probability of VAP. Every patient underwent both procedures, in a formally randomized fashion. The interpretation of quantitative cultures was done in a blind fashion.Setting. Single center study, with a 20 bed medical and surgical Intensive Care Unit of the University Hospital in Monterrey, Mexico.Patients. Twenty-five patients with high probability of VAP.Interventions. Every patient underwent blind bronchoalveolar lavage with a modified nasogastric tube, and a bronchospic-guided bronchoalveolar lavage.Results. Twenty-one patients underwent both procedures. Four patients were excluded due to contamination of the cultures. The quantitative cultures were compared in a paired fashion. Only two patients had discordant cultures. The correlation coefficient between the number of colonies was very high, r = 0.90 (95% confidence interval [CI], 0.77-0.96; p = 0.0001). Conclusiones. El lavado broncoalveolar ciego con sonda nasogástrica modificada es una herramienta de mucho valor para la identificación del agente etiológico en NAV, especialmente cuando un broncoscopista experto o los recursos necesarios para lavado broncoalveolar guiado con broncoscopio no están fácilmente disponibles. Conclusions. The blind bronchoalveolar lavage with a modified nasogastric tube is a valuable tool for the identification of etiologic agent in VAPPALABRAS CLAVE: neumonía asociada a ventilador, lavado broncoalveolar, sonda nasogástrica, lavado broncoalveolar ciego.