Background: Pneumonia is one of the most common nosocomial infections in hospitalized patients. The risk of nosocomial pneumonia increases with age severity of acute illness and preexisting co-morbid conditions. Ventilator-associated pneumonia (VAP) significantly increases morbidity length of stay resource utilization and mortality. The purpose of this study was to determine whether adherence to a ventilator weaning protocol (WP) and the use of chlorhexidine gluconate (CH) oral rinse for oral hygiene would decrease the incidence of VAP in surgical ICU patients. Methods: A prospective study was conducted over a period of 10 months (October 1998-July 1999) in surgical ICU patients requiring mechanical ventilation (n = 95). During the first 5 months a WP was applied to all patients requiring mechanical ventilation. During the following 5 months a CH 0.12% oral rinse administered twice daily was added to the protocol initiated on ICU admission in all intubated patients. The data collection included age gender race risk factors co-morbid conditions severity of the acute illness (APACHE II) at admission duration of ventilation ICU and total-hospital length of stay and incidence of VAP and in-hospital mortality rates. Both WP and WP + CH groups were compared using the National Nosocomial Infection Surveillance (NNIS) and hospital databases as historic controls. Results: The institution of the WP alone led only to a slight decrease in the incidence of VAP but a significant reduction in the median duration of mechanical ventilation by 40% (4.5 days p < 0.008). The addition of CH to the WP led to a significant reduction and delay in the occurrence of VAP (37% overall 75% for late VAP p < 0.05). The median duration of mechanical ventilation in this group was similar to that of the WP group. There was no significant difference in the overall hospital or ICU length of stay between the groups. Conclusions: Improved oral hygiene via topical CH application in conjunction with the use of a WP is effective in reducing the incidence of VAP and the duration of mechanical ventilation in surgical ICU patients.