To evaluate the use of a tool for pain assessment in cognitively impaired adults. A multi-dimensional tool was implemented and evaluated in relation to use rate; frequency of specific pain indicators; staff perceptions of advantages and disadvantages of pain assessment in this patient group; and factors that aid or impede this assessment. Some indicators are more likely to be observed and documented. There was a lack of compliance by nurses in making and recording pain observations on every shift. Observations that were recorded occurred most frequently on the morning shift. Factors that were identified as assisting in the assessment of pain related to nursing staff having the appropriate knowledge and skills gained through experience of caring for cognitively impaired adults. Pain assessment for cognitively impaired adults should continue to be based on a combination of physiological and behavioural indicators. Assessment should be conducted as indicated by the nurse's clinical judgement and follow-up pain assessment should be undertaken after implementation of appropriate comfort measures.