This study examines registered nurse perceptions of their role in acute care hospitals that use nursing care assistants (NCA) and unlicensed assistive personnel (UAP). Also studied was registered nurse (RN) satisfaction with nursing care assistants and unlicensed assistive personnel in the United Kingdom (UK) and the United States of America (USA). The purpose of this study is to assist RNs and managers in the re-design of health-care delivery systems by investigating: 1. The differences and similarities of registered nurses in the UK and the USA in the perceptions of changes in the RN role when working with nursing care assistants or unlicensed assistive personnel. 2. The differences between and similarities of registered nurses in the UK and the USA in perceptions of NCA and UAP abilities to perform delegated duties, to communicate pertinent clinical information and to provide more time for professional nursing activities. Registered nurse perceptions in the UK were compared with the findings of a previous study of RN role changes and satisfaction in the USA. Registered nurses in the UK did not perceive a profound change in their role when working with UAP and were more satisfied with their use than were RNs in the USA.