This paper reports a study analysing the various functions of nurses' documentation of patient assessments.Modes of documentation have received much attention in the nursing press since the integration of the nursing process and nursing models. Previous research has shown that current documentation practices do not consistently promote effective communication and evaluation of patient care. A recent systematic review found no evidence that any particular system of documentation improved this situation. However, nurses' documentation serves not only to communicate information to others, but also has a political function as a presentation of what is important and ethically 'right' to report.A Foucauldian approach to discourse analysis was used to analyse 45 patient records.The findings indicate that nurses employ three discernible discursive practices in the documentation of patient assessments: medical, nursing and informal. Each practice has an effect on the presentation of nursing in the documentation. Because of the complex interplay between these practices, nurses present themselves as aligned with the medical profession, as distinct and professional, and as informal in their descriptions of non-biological information. The use of these practices appears to be motivated by the type of information being reporting.Existing literature highlights the functional aspects of nursing documentation. In contrast, this paper explores the way in which nurses, through their documentation, constitute themselves and the nursing profession. In this way, nursing documentation is viewed as a social practice and a conduit through which particular power effects are produced and reproduced, rather than simply a matter of, for example, knowledge, individual choice or good practice.