Insufficient nursing staff levels have been shown to have a negative impact on the quality of care, increasing patient morbidity and mortality. In order to address the issue of how Switzerland can avail itself of sufficient nursing staff in the medium-term and despite ageing of the population, it is necessary to have information on certain key factors. How many people with training in nursing stay in the health sector throughout their working life and why do other nursing staff leave their original career field? The nurses at work study aimed to discover the reasons why nursing staff remain in or leave their profession or more specifically, the health sector. Its goal is to find ways of retaining more nursing staff in the profession. Despite tremendous efforts, it proved extremely difficult to get in touch with men and women who had left the healthcare system: today we can only conclude that this group is under-represented in the study. This conclusion is backed up by data from the Federal Statistical Office’s Structural Survey). Nevertheless, the findings of nurses at work are very useful as qualitative research and should be made available to the public and in particular to authorities in charge of staff planning. The results pinpoint which aspects of the nursing profession should be taken into account when making endeavours to retain as many nurses as possible in the health sector.