Previous research investigating shift work and its impact upon the quality of registered nurse performance and outcomes (including biological, psychosocial and organizational) is reviewed. The present study, which involved non-participant observation of staff nurses (n = 34) within their first year of practice (Part 1 or Part 12 of the United Kingdom Professional Register), is described. The findings demonstrated support for earlier research which suggested that 12 1/2 hour shifts are associated with less effective performance. This study, together with previous research, highlights important indicators for the design and management of future empirical work which is required to investigate the influence of shift work upon process as well as outcomes for nurses, service users and the employing organization. This is particularly pertinent in the light of recent changes in work patterns. The well-being and effectiveness of the nursing workforce requires enhancement, and the effective management of shift-work is a key strategy in achieving this.