This is a report of a research protocol to assess level, determinants and consequences of stress in NHS-24 telephone helpline nurses. Nurses working in traditional hospital settings report high levels of occupational stress. Many nurses now work in call centres, environments with their own inherent stressors. Stress in nurses has been linked to reduced physical and psychological health, reduced job satisfaction, increased sickness absence and turnover, and poorer job performance. In this study, we will use multiple methods, including real time data collection to assess stress in telephone helpline nurses. During 2008/09, NHS-24 nurses will (a) report general stress and call-by-call stress over two working shifts, (b) complete measures of theoretical determinants of occupational stress (demand, control, effort and reward), (c) have their concentration and attention tested before and after two shifts, (d) have their heart rate monitored over two shifts, (e) report job satisfaction, absenteeism and intended turnover and (f) allow the research team to retrieve related call data and performance indicators. Relationships between the variables will be assessed using regression and multi-level modelling. Data will be analysed to examine the relationships between reported stress, physiological aspects of stress, call type, workplace attributes, cognitive performance, job satisfaction and absenteeism. The analysis will test models of occupational stress and assess the effects of stress on multiple work outcomes. The results will inform theoretical understanding of nurse stress, its determinants and possible methods of management. The practical challenges of conducting such a comprehensive study in a clinical environment are discussed.