The application of oropharyngeal chlorhexidine is mainly active on Gram-positive microorganisms with only a minimal impact on colonisation by Gram-negative microorganisms. Seven randomized clinical trials have been published that showed a significant reduction in ventilator associated pneumonia (VAP) incidence, but not on survival. Some questions remain unanswered: it is presently unclear whether patients who benefit can be selected from the population at risk, and optimal formulation and dosage of chlorhexidine has not yet been established. International recommendations for using oro-pharyngeal topical chlorhexidine in ventilated patients have now been roborated by two Dutch studies.