The importance of using verbal communication in the care of critically ill patients has long been known. Both qualitative and quantitative studies have presented evidence of the benefits of effective communication. This non-participant observational study aimed to explore how much and what types of verbal communication critical care nurses use when caring for unconscious or sedated patients. Sixteen critical care nurses were observed in 4-hour episodes and their verbal communication was transcribed and timed at source. Seven categories of verbal communication and a 'core concept' emerged on analysis of the raw data. Medical investigations/interventions performed on the patients increased the amount of communication used. The participants in this study were found to use a greater variety and amount of verbal communication than participants in other studies. The findings of this study highlight the need for formal support systems and continued education for nurses about the benefits of verbal communication.