Elderly patients are vulnerable to complications of intravenous fluid overload, however daily monitoring of fluid balance in this population has been highlighted as sub optimal by the NCEPOD. We compare current practice in fluid balance monitoring and intravenous fluid prescribing for elderly patients in a London District General Hospital to guidelines for fluid management in children issued by the National Patient Safety Agency.This study consists of two parts: (1) a ward-based survey of fluid balance monitoring in all patients above the age of 65 receiving intravenous fluids; (2) an anonymous questionnaire completed by 20 doctors of a variety of grades and specialities on the parameters of fluid balance routinely checked by doctors prior to prescribing intravenous fluids.The results highlight that the most frequently monitored parameters of fluid balance are daily serum urea, creatinine and sodium levels (65.1% of patients receiving intravenous fluids on the wards, 85% of doctors check these levels before prescribing fluids). Initial weight is measured in one quarter of patients; daily weight is monitored in 9.4% of patients and 25% of doctors check daily weight before prescribing intravenous fluids.Initial and daily weights are non-invasive parameters of fluid balance that are infrequently monitored in elderly patients receiving intravenous fluids. We propose that all elderly patients should be weighed (1) on admission to the Emergency Department, (2) prior to commencement of intravenous fluids and (3) on a regular basis, preferably daily, for the duration of intravenous fluid administration. For immobile patients, strict fluid input–output charts should be maintained as a surrogate index of changes in daily weight. We encourage consistent and accurate documentation of these non-invasive parameters on the fluid prescription charts.