Introduction: Gastrointestinal stromal tumors (GISTs) are considered the most common mesenchymal tumors of the gastrointestinal tract, representing 1% of gastrointestinal malignancies. But to our knowledge has never been reported to be associated with diabetes insipidus (central or nephrogenic). Case Report: A 68-year-old female was admitted to hospital for investigation of delirium associated with polydipsia and polyuria. She developed hematemesis in hospital which required further investigations. Patient was found to have GIST, diagnosed histologically, associated with diabetes insipidus. She required ICU admission and developed nosocomial pneumonia. Despite appropriate treatment, our patient died. Conclusion: Gastrointestinal stromal tumors usually present as subepithelial neoplasms of gastrointestinal tract (GIT). However, there has been no association described so far between GISTs and diabetes insipidus and needs further work up to evaluate the link between the two entities.