By accurately assessing a patient's conscious level, the nurse is able to detect neurological changes in order to improve survival outcomes and minimize long-term sequelae. However, problems are encountered when using the Glasgow Coma Scale (GCS) to assess a patient's conscious level. This study aims to identify the profile of a group of nurse's knowledge, attitudes and self-confidence (KAS) to perform the conscious level assessment using the GCS. A descriptive correlational survey was conducted from January to March 2010 in one acute care hospital in Singapore. A convenience sampling was used, and 114 nursing staff (91.2% response rates) completed a self-reported questionnaire. Four main outcomes: demographic and clinical experiences, and KAS. Two-step cluster analysis yielded two clusters. Cluster A (48.2%) was labelled ‘average attitudes, knowledge and self-confidence’ group. Cluster B (51.8%) was labelled as ‘positive attitudes, good knowledge and high self-confidence’ group. Two clusters showed differences in the levels of their KAS. Findings may be used for management to improve support of nurses to ensure accurately assessing patient's conscious level. Management should formulate strategies to encourage nurses to resolve actual problems following training or mentoring and to increase the depth and breadth of nurses' KAS to perform the conscious level assessment using the GCS.