A cross-sectional survey of inpatient palliative care subjects (n = 52) was performed to determine the severity and distribution of symptoms thought to be associated with dehydration in terminally ill cancer patients and to clarify the association between the severity of these symptoms and commonly used objective measures of dehydration. Each patient rated the severity of seven symptoms using 100-mm visual analogue scales. The symptoms considered were thirst, dry mouth, bad taste, nausea, pleasure in drinking, fatigue, and pain. Associations were sought between these symptoms and predictor variables (fluid intake, plasma osmolality, sodium, and urea) and confounding variables (age, medications, oral disease, and mouth-care regimen). Mean symptom ratings were thirst 53.8 mm, dry mouth 60.0 mm, bad taste 46.6 mm, nausea 24.0 mm, pleasure in drinking 61.6 mm, fatigue 61.8 mm, and pain 33.5 mm. Using multiple-linear regression, no association could be demonstrated between thirst (the principal outcome of interest) and the predictor or confounding variables. Estimates of the study power performed after completion revealed a 76% chance of detecting a 20-mm difference between high and low fluid intake groups. This study provides the first quantitative estimate of the experience of dehydration symptoms in those with advanced cancer. The symptoms appear to be rated moderately severe, but there is no demonstrable association between severity and fluid intake. Further studies with greater statistical power and more accurate hydration assessment would strengthen our understanding of this association.