Hyponatremia has been known as an important predictor of clinical outcomes in patients with heart failure (HF). While information on hyponatremia in patients with HF has been available abundantly, information on factors associated with increased risk of developing hospital-acquired hyponatremia (HAH) is still limited. Objective To identify patients and medication-related factors associated with HAH in patients hospitalized from HF. Setting Fatmawati Hospital in Jakarta, Indonesia. Methods This is a nested case-control study with patients developing HAH served as case group and each patient in case group was matched by age and gender to three patients in control group. Patients included in this study are patients hospitalized from HF, and coded with I.50 according to ICD-10, during 2011-2013 at Fatmawati Hospital in Jakarta, Indonesia. Information retrieved from patients' medical records included demographic profiles, vital signs and symptoms at admission, past medical history, medication during hospitalization and clinical chemistry laboratory records. Multivariable logistic regression analysis was performed to find out patient and treatment-related factors associated with the development of HAH.