BACKGROUND: Do Not Attempt Cardiopulmonary Resuscitation (DNACPR) orders have been shown to be independently associated with patients receiving fewer treatments, reduced admission to intensive care and worse outcomes even after accounting for known confounders. The mechanisms by which they influence practice have not previously been studied. OBJECTIVES: To present a rich qualitative description of the use of the DNACPR form in a hospital ward setting and explore what influence it has on the everyday care of patients. DESIGN: Multi-source qualitative study, primarily using direct observation and semi-structured interviews based on two acute wards in a typical middle-sized National Health Service hospital in UK. RESULTS: The study identified a range of ways in which DNACPR orders influence ward practice, beyond dictating whether or not cardiopulmonary resuscitation should be attempted. Five key themes encapsulate the range of potential impacts emerging from the data: the specific design and primacy of the form, matters relating to clinical decision making, staff reflections on how the form can affect care, staff concern over 'inappropriate' resuscitation, and discussions with patients/relatives about DNACPR decisions. Overall, it was found that while the DNACPR form is recognized as serving a useful purpose, its influence negatively permeated many aspects of clinical practice. CONCLUSION: DNACPR orders can act as unofficial 'stop' signs and can often signify the inappropriate end to clinical decision making and proactive care. Many clinicians were uncomfortable discussing DNACPR orders with patients and families. These findings help understand why patients with DNACPR orders have worse outcomes, as such they may inform improvements in resuscitation policies.