OBJECTIVES: The objective of this study was to quantify, for the first time in a Spanish population, the time and cost burden of informal care for patients with heart failure. METHODS: A descriptive analysis of a multicenter, prospective observational study was performed. Patients who met inclusion criteria were followed-up for a period of 12 months, with 3 visits programmed at baseline, 6 months and 12 months. A total of 9 Spanish hospitals were involved in the study. Baseline characteristics and caregiver’s information were registered for every patient. Once identified total hours, the replacement cost method was used. RESULTS: A total of 450 patients were included, 76% men, mean age was 62.6 years. 66.1% were in NYHA class II, 32.7% NYHA class III and 1.1% NYHA class IV. Prevalence of ischemic cardiopathy was 33.5%. Thirty-five percent of patients had an implantable device (ICD, RCT or pacemaker). One-third needed support for daily activities. One-hundred and one informal caregivers were identified, mean age of 57.6 years, mostly women (84.1%). Main relationship with caregiver was spouse/couple (74.2%), followed by son/daughter (16.6%). Number of weekly hours of caregiving was estimated at 42.5 hours (39.46 hours for patients NYHA class II and 47.39 hours for patients NYHA class III-IV) and shadow prices values from €9 to €12 per hour. Total costs associated to informal caregiving increases between €19,897 and €26,530 (€18,466 - €24,621 for patients in NYHA class II and €22,178 - €29,571 for patients in NYHA class III or IV). CONCLUSIONS: Approximately one-third required support from an informal caregiver, which represents a significant burden for society and often has not been accounted for in economic evaluations of treatments for heart failure. Costs for informal care appear to increase with worse disease severity as measured by NYHA class.