A randomised controlled pilot trial is proposed. The study aims to recruit 120 patients across a network of dialysis units, focussing on patients who have higher than average interdialytic weight gains (IDWG). The trial is designed to build upon routine education about fluid management during dialysis visits, and will compare a group of patients who have received a self-affirmation intervention to boost their sense-of-self (self-affirmation arm) to a control group (control arm). It is expected that patients in the self-affirmation arm should have a more positive evaluation of the health-risk information about fluid management, feel more able to, and intend to change their fluid control behaviour. The appropriate methods of analysis include logistic regression, and mixed multilevel models, but the relatively small sample size will limit the extent of the modelling that can be undertaken. Thus the aim of the analysis will be examine the size of the observed effects and to design a larger study. The study will inform the extent to which psychological and clinical factors contribute to the outcome and should be used in future studies.