Objective. To assess the knowledge of nurses working in intensive care units (ICUs) in respect of pain management, glycaemic control and weaning from mechanical ventilation.Methods. An analytical, cross-sectional survey design was used. All ICU-trained and non-ICU-trained registered nurses (N=136) working in the ICUs of selected public and private hospitals were invited to participate. Results. The knowledge of both the ICU-trained and non-ICU-trained nurses was found to be lacking. The overall mean score (standard deviation) obtained was 47.56% (11.61). The ICU-trained participants obtained 50.11% (11.96) and non-ICU-trained participants obtained 45. 01% (10.75). This difference, although small, was statistically significant (p=0.0099). A poor relationship was found between level of knowledge and years of ICU experience. Conclusion. Nurses lack knowledge in the three care areas tested. ICU nurses' experience cannot be relied upon as a source of knowledge for decision-making about protocol-directed care. It is suggested that on-going educational programmes be introduced into ICUs to address this shortfall in knowledge.