Currently, a standard HD prescription includes a specific volume of ultrafiltration, set to achieve a clinically derived estimate of 'target weight'. Acutely, hypervolaemia (fluid overload) can be life threatening, whilst chronically it is associated with hypertension and an increased cardiovascular risk. Accordingly, target weight is typically prescribed to allow for interdialytic weight gains. The sequential reduction of target weight to achieve the lowest possible target weight (dry weight probing), thought to improve blood pressure (BP) control, left ventricular mass index and long-term outcomes, is favoured by many nephrologists. However, this results in dehydration and is associated with increased intradialytic symptoms, including intradialytic hypotension, which itself brings an increased risk of cardiac death. Local data from the Wessex Kidney Centre suggests that patients experiencing a greater drop in systolic BP pre- to post-dialysis are more likely to experience symptomatic hypotension during dialysis. Intradialytic BP variability is also detrimental to long-term outcomes. Achieving ideal hydration is therefore important for not only reducing symptomatology, but also improving BP control and cardiovascular health in these patients. Poor cardiovascular health contributes to the reduced physical function characterising this group, which along with physical (in)activity is associated with a poorer prognosis in this patient group. Furthermore, increased rates of depression and cardiovascular disease have been associated with poor physical function in this group.